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The Helix 511

FIGURE 1 This is the HX511 fanless computer. It’s pretty heavy due to the massive heatsink that also serves as the unit’s enclosure.
Written by Brian Millier

A Review of OnLogic’s New Fanless Industrial Computer

OnLogic has been making industrial computer products for 20 years now, and the Helix 511 (HX511) Fanless Industrial Computer is a new addition to their product line. This month, Brian reviews that model.

  • What is a good new industrial fanless computer?
  • What are the features OnLogic’s Helix511?
  • What are the advantages and drawbacks to OnLogic’s Helix511?
  • OnLogic Helix511 Industrial Fanless Computer

The Helix 511 (HX511) unit consists of a common motherboard mounted in a heavy, heatsinked enclosure. Figure 1 is a photo of the HX511’s front panel—you can see that the enclosure is basically one massive aluminum heatsink. It is about 7” wide, 10” long and 2” in height. Figure 2 is a photo I took after unpacking the HX511 review unit, which was equipped with most of the available options.

This is the HX511 fanless computer. It’s pretty heavy due to the massive heatsink that also serves as the unit’s enclosure.
This is the HX511 fanless computer. It’s pretty heavy due to the massive heatsink that also serves as the unit’s enclosure.
FIGURE 2 Here are all of the items received with the review unit. The HX511 is extremely well-padded in the shipping box. Note how large the Wi-Fi antennas are!
Here are all of the items received with the review unit. The HX511 is extremely well-padded in the shipping box. Note how large the Wi-Fi antennas are!

Beyond the common motherboard and enclosure, the customer can specify how they want their unit to be configured. The build is done at OnLogic’s Vermont operation and the build time is normally three to five business days, but you can pay extra for a one to two day build. Before getting into the industrial-focused IO capabilities, let’s first look at the standard computer features available on the HX511.

The motherboard contains an LGA1700 socket which can accept various Alder Lake 12th generation Intel processors. At the low end, an Intel Celeron 7305 5-core processor is offered. If more power is needed, an i3-12300HL, i5-12600HL, or i7-12800HL processor is available. All three of the latter are 45W Total Dissipated Power (TDP) processors. These Intel Hybrid processors are optimized for lower-power consumption (in other words, less heat) and are commonly found in laptops, mini-PCs, and so forth. While not as fast as the Intel Core processors that would generally be found in full-size desktop computers, they are certainly capable of handling most industrial use cases—especially at the i7-12800HL option level. For interest’s sake, Figure 3 shows benchmark results of the i7-12800HL contained in the HX511 review unit, compared with the 6th generation i7 contained in my older, top-of-the-line Dell desktop computer. The HX511’s i7 is 207% faster in multi-core operations.

Referring to Figure 4, this is a photo of the review unit’s motherboard—as seen with the HX511’s bottom cover/heatsink removed. All units have two sockets for 4800MHz DDR5 modules. On the HX511’s configuration webpage, it shows purchase options for 8, 16, and 32GB SO-DIMM modules, in quantities of either one or two. That indicates to me that one could populate only one socket and the unit would still operate. Thus, the unit can be ordered with between 8 and 64GB of memory. The placement of the two SO-DIMM sockets allows them to be coupled to the HX511’s aluminum bottom panel with thermal pads, so there shouldn’t be any memory speed throttling which could occur if the modules started to get too hot for full-speed operation.

For curiosity’s sake, I checked out a benchmark comparing the i7-12800HL contained in the review unit, with the i7-6700 contained in my older, high-end Dell desktop PC. In multi-core use, the HX511’s Hybrid i7 is more than twice as fast.
For curiosity’s sake, I checked out a benchmark comparing the i7-12800HL contained in the review unit, with the i7-6700 contained in my older, high-end Dell desktop PC. In multi-core use, the HX511’s Hybrid i7 is more than twice as fast.
This is a photo of the HX511 motherboard, as seen with the bottom cover removed.
This is a photo of the HX511 motherboard, as seen with the bottom cover removed.

Primary storage comes in the form of an M.2 SSD drive. Storage sizes between 64GB and 2TB can be ordered. The M.2 M-key socket containing the primary storage that came with the review unit (a Transcend 256GB SATA SSD) can accept SATA (up to Gen 3) or NVMe SSDs. NVMe SSDs are more commonly available, faster, and somewhat more expensive than their SATA counterparts. The HX511 also contains one M.2 B-key socket (unused in the review unit) which can handle either a SATA SSD, or the cellular modem card.

For networking, two 2.5Gbps Ethernet ports are standard, which are implemented with Intel I225 LAN chips. The primary Ethernet port uses an I225-LM chip which supports Intel Active Management Technology (AMT), allowing for remote monitoring, maintenance, and repair of the system. I have a 500Mbps ISP fiber connection, and I measured between 550 and 600Mbps using the HX511’s Ethernet port.

Wi-Fi/Bluetooth communication is not standard but is available by adding a card that plugs into an M.2 E-key socket. This uses the Intel AC 9260 Wi-Fi controller which handles all of the common Wi-Fi protocols on both the 2.4 and 5GHz bands. It also implements Bluetooth 5.1. This option adds two RP-SMA sockets to the enclosure. This LAN controller supports MU-MIMO with two receive and two transmit streams, so I expect that’s why two antenna sockets are provided. The review unit came with two antennas. As you can see from Figure 2, these are larger than you would normally expect for an antenna covering the 2.4 and 5GHz Wi-Fi bands. The HX511 Wi-Fi worked fine in my office using the 2.4GHz band. Speeds of 50-70Mbps were obtained, which is identical to the speeds I get in my office using other Wi-Fi devices. While my router handles the 5GHz band, the 5GHz signal doesn’t travel the 50 feet between the router and my office.

Cellular connectivity is also an option. This consists of an AMIT 4G LTE modem and would result in an additional SMA antenna socket being mounted on the enclosure. A separate cellular antenna would need to be ordered, in this case. I didn’t request this option since I had no existing cellular data plan to test it with. Note that if this option is chosen, it must be plugged into the motherboard’s M.2 B-key socket, since that socket has the front panel-mounted SIM card socket wired to it. So, if you need the cellular modem, you would not be able to mount two SSDs, since one of the SSDs would need to go into this socket.

The HX511 has plenty of USB ports to handle a keyboard, mouse, and many other common peripherals. There are four USB 3.2 ports on the front panel capable of up to 10Gb/s transfer rates. There are also two Thunderbolt 4 ports. Thunderbolt is basically a superset of USB-C, so those ports add two more USB-C ports. When used as USB-C ports, the left one can source 5V/3A and the right one can source 5V/1.5A. They are also capable of 10Gb/s USB transfer rates.

The two Thunderbolt 4 ports are also capable of driving video displays because they are DisplayPort 1.4 compliant. I used an iCAN TC056 Multiport Adapter on one of the Thunderbolt ports to drive one of my 1920×1080 HDMI display monitors (in addition to the two I had connected to the DisplayPort video outputs). The TC056 is no more expensive than a Thunderbolt-to-HDMI cable, but also provides a USB-C charging port and a USB-A socket.

The HX511 comes with two DisplayPort sockets. These are each capable of up to 4096×2304 resolution at 60Hz. These ports are Dual-Mode DisplayPort (DP++) ports. This means that you can connect an HDMI video display using only a passive DisplayPort-to-HDMI cable. These cables are commonly available, but OnLogic can also supply them (SKU CBV112). While I’m not sure how often 4K resolution is needed in an industrial setting, I use a large 4K monitor on my office computer, and the HX511 drove it nicely. The DisplayPorts also support Multi-Stream Transport.

As an industrial computer, I doubt that an audio output would be high on the list of requirements. The HX511 does not contain a sound card of any type. However, the HDMI video protocol includes an I2S stream. You can get HDMI monitors that have at least a headphone jack and possibly built-in speakers. I tried this out using an HDMI monitor connected to the HX511’s DisplayPort, and sound came through the headphone jack properly. If your monitor has audio capability, it will show up as a sound output choice in the Sounds section of the Windows 11 Settings app. This should also work with DisplayPort monitors, but I did not have one to try out. However, in the HX511 Product Manual, Appendix G, OnLogic states that DisplayPort audio doesn’t work in Ubunto 22.04 Desktop.

From Figure 4, you can see that the battery for the Real Time Clock is enclosed in a pouch and connected to the motherboard via a 2-pin header. At first I thought this was odd, expecting a socket on the motherboard which is normal on a desktop PC. However, in the HX511, the BIOS contains a lot of configuration information specific to the IO ports. These might be hard to recall after the unit has been in operation for 5-10 years (the normal life of a CR2032 coin cell). Therefore, one would want to replace the CR2032 while the computer was still powered up, in order to leave the BIOS information intact. From experience, I know that removing a coin cell from a PC board-mounted socket can result in it popping out and landing somewhere on the board, where it could cause a short circuit. That is not going to happen with the arrangement used in the HX511.

Since the HX511 is an industrial computer, there are a number of mounting options that can be ordered for it. These are:

  • A Wall mount (SKU MTW101)
  • DIN Rail mount (SKU MTW101-K)
  • VESA mount to the back of a monitor (SKU VMPL-2022-K)

There is no AC mains power supply in the HX511 enclosure. Instead, it expects 12-24VDC to be supplied to a four-pin terminal block connector on the rear panel. This socket mates with a Dinkle 2ESDAM-04P plug (or equivalent) which is a 0.2” pitch connector capable of handling 15A per contact. I couldn’t find this Dinkle part number at DigiKey, but the Molex 0395305004 appears to be equivalent.

OnLogic offers two power supply “brick” options for the HX511. They are both 24VDC with current capacities of either 13.75A (330W model) or 7.5A (180W model). I received the 330W power supply with the review unit. While they call laptop power supplies “bricks,” the HX511 330W power supply is actually approaching the size of a “real” brick: 4” wide x 8” long x 1” thick.

If you look closely at Figure 2, you can see that there is an intermediate “pigtail” cable (sitting on top of the power brick) that adapts the power brick’s standard Molex connector (white) to the 4-pin Dinkle connector. OnLogic uses the power brick for various computer models, not all of which use the same DC input socket, so they adapt it using that pigtail assembly.

While the HX511’s power connector is a 4-pin connector, only two of the pins are used for power. The other two pins can be connected to an N.O. momentary contact switch which will duplicate the function of the momentary pushbutton on the HX511’s front panel. If the HX511 is embedded in a larger unit, this is handy. Also, if you have selected the 3 COM option, there will be a 34-pin header connector on the front panel. Most of this connector is taken up with the signal/handshake lines dedicated to the three COM ports. However, pins 30-34 can be used to connect various switches (power and reset) and status LED signals (power and disk activity). These also make it easier to monitor an HX511 that is hidden away in some larger piece of equipment.

With that intermediate pigtail section of the power supply cable, I figured it would be easy to tap into it to do a power consumption test. However, OnLogic has already done some comprehensive power consumption testing, so I relied on that instead. In Appendix A of the Product Manual, they have reported tests done on three separate HX511 configurations. The “Config 4 High” test came the closest to matching the review unit—the test configuration had twice the RAM and a second SSD but was otherwise identical to the review unit. Table 1 shows the results of this testing. With Windows 11 Pro running, but at idle, the power consumption was only 12.9W. Running system processor stress test software, this rose to 28W. During periods of the test in which the i7 ran in Turbo mode, the power maxed out at 140W. I doubt that industrial users care much about the exact power consumption in various sleep modes (S5, Deep S5, Pseudo G3) but you can see that the switching regulators on the HX511’s motherboard have little quiescent current draw: the power consumption in sleep mode is very low and doesn’t change that much whether the HX511 is supplied with 12V or 24V. The switching regulators, required to provide all of the different power supply voltages for the processor and logic, are located on the side of the motherboard that faces the top panel/heatsink. They’re hidden, but I expect they are thermally coupled to this heatsink.

This shows the power consumption values that OnLogic obtained for an HX511 configured basically the same as the review unit.
This shows the power consumption values that OnLogic obtained for an HX511 configured basically the same as the review unit.

The power consumption test results show a maximum current draw of 140W (in turbo mode). While the tests cited above don’t include power that could be supplied by all four USB and two Thunderbolt ports, they would contribute a maximum of about 40W if every USB/Thunderbolt port was supplying its maximum rated amount of current. For all models except ones with an i7 and fitted with all available options, the 180W power brick would be fine. However, OnLogic sells the 330W model for the customer who wants more power reserve for the fastest and most completely configured models.

While I was performing scope tests on the COM ports, I wondered whether I would need to connect up the scope probe’s ground wire. On a desktop PC (and any device that is plugged into its USB port), both the scope and the desktop PC are AC mains ground-referenced, so the scope probe’s ground wire isn’t needed. However, a laptop power brick has its DC output floating with respect to AC mains ground. In this respect, the HX511 power brick differs—its negative DC terminal is connected to the AC mains ground. So, the HX511 is ground-referenced like a desktop PC, and there is no provision on the HX511’s case for a stud to attach a ground wire.

The HX511’s power supply regulator circuitry contains undervoltage monitoring which shuts the system down if the input voltage drops below 6.5V. At the other extreme, the maximum DC input voltage (with no system damage) is 28.4V.


Assuming that you don’t order a bare-bones system (that is, with no SSD installed), OnLogic will install an OS image on the included SSD. There are five choices currently available:

  • Windows 11 Professional 64-bit
  • Windows 10 IoT Enterprise 2021 LTSE Value 64-bit (Celeron.i3, i5 only)
  • Windows 10 IoT Enterprise 2021 LTSE High-end 64-bit (i7 only)
  • Ubunto Desktop 22.04 LTS 64-bit IoT image
  • Ubunto Server 22.04 LTS 64-bit IoT image

OnLogic confirmed that most industrial users would opt for one of the versions of Ubunto listed above. The Ubunto OS is available for $10, whereas Windows 10 or 11 costs about $200. Since I use Windows on a daily basis, and am only moderately comfortable with Linux, I requested that the HX511 be equipped with Windows 11 Pro—to simplify my review process. With Windows 11 Pro loaded, 177GB of the 256GB SSD was available for apps, and so on.

With the pre-loaded Windows 11 Pro image, you must go through Microsoft’s standard setup process to configure the OS for your personal identity and preferences. Microsoft expects you to establish a Microsoft account, which in my case, I already had for several of my other PCs. Microsoft also encourages you to define a six-character PIN, which speeds up the login process, whenever you boot up the computer.

In an industrial setting, you might want to retain some form of sign-in authentication when the computer is either rebooted or powered up. In this case you would want to leave this sign-in intact. However, the HX511 BIOS allows you to select an option in which the HX511 boots up automatically when mains power is applied. That is, you don’t have to press the momentary power pushbutton to turn it on. In this instance, the HX511 might be unattended (after a power failure for example), so the Windows sign-in would block the HX511 from executing whatever application it would normally be running. In this case, you would want to remove this sign-in authentication.

This can be done by running the app Netplwiz and selecting the account name that you have established. There should be an option box titled “Users must enter a user name and password to use this computer.” Uncheck this box and hit Apply. If this option box is not visible, it means that you have set up the PIN sign-in option. This must be removed by opening Settings > Accounts > Sign-in Options and turning off the option that reads “For improved security, only allow Windows Hello sign-in for Microsoft accounts on this device.” Then, re-open Netplwiz and complete the procedure as outlined above.

After you have setup Windows 11 Pro, you can start using the computer, but if you enter the Setup app, you’ll see the message “Windows is not activated—no numbers found on the computer ER 0xC004F213.” You must select “Switch to a different product key” and type in the number on the Microsoft label, found on the bottom panel of the HX511. The product key is partially obscured by a scratch-off label—don’t scratch too hard or you may obscure the product key characters underneath.


Back when personal computers first arrived, we all had to become familiar with the computer’s BIOS settings—your hard disk wouldn’t operate unless you went into the BIOS and configured it properly in terms of heads, cylinders, sectors per track, and so on. With modern consumer PCs, most users no longer have to deal with the BIOS, as most PCs come configured with the proper defaults, and newer SSDs and hard disks are recognized automatically.

With an industrial PC, there are many necessary and useful settings that are configured in the BIOS. OnLogic uses a version of the InsydeH2O BIOS, customized for their computers. From the factory, the HX511 BIOS splash screen just displays the OnLogic logo without showing the BIOS entry keystroke required. One of the common choices, the DELETE key, gets you in. Even if you’re quite familiar with PCs, the sheer number of configuration options that are available in all the menus is somewhat overwhelming. Therefore, OnLogic provides a BIOS Manual [1]. This is a 40-page document that shows all of the BIOS options, and explains many of the more useful ones. For example, the evaluation unit came configured to boot up automatically when power is applied to the power supply brick. In an industrial setting, this might be necessary, but in some scenarios, it might be dangerous to have the computer power up and resume operations when power is restored.

When you enter the BIOS, the front page screen is shown. Most of the choices are self-explanatory. It is the Setup Utility where most of the HX511’s configuration options are found, and many of them are in the Advanced menu selection.

So, to configure the way that the HX511 acts when power is restored after a power failure, for example, you enter the Advanced > PCH-IO Configuration section and select the topic “State after G3.” I don’t think I would have guessed that this is where this setting would be made, but it’s highlighted as one of the commonly used settings.

Similarly, it’s quite conceivable that, while you might want the option of booting from a USB flash drive to be available to service technicians, you would want this feature turned off, in general, to prevent a stranger from popping in a USB flash drive and doing something malicious. This isn’t in the Advanced settings but is in the Boot tab of the BIOS home page.

The Advanced > OnLogic Feature Configuration section contains settings for the Intel I225 Ethernet Network Adapters. These adapters can be enabled/disabled here, as can a Wake on Lan function. Also in this section is the option of enabling/disabling a feature known as Pseudo G3. This governs how the CPU will go into a low-power mode when the computer is running on battery backup, when it is normally supplied with mains power. I don’t believe that this applies to the HX511.

Immediately following the Advanced > OnLogic Feature Configuration is the SIO NCT5124D section. This is the section of the BIOS where both the 1 COM and 3 COM option boards, which add RS232/422/485 serial ports, are configured. The COM ports are described in the next section.

The HX511 can be woken from various sleep states by five different hardware sources. Some of these are configured in the BIOS. Table 2 shows how these events are handled.

These are the five sources of Wake-up events that the HX511 can respond to.
These are the five sources of Wake-up events that the HX511 can respond to.

The optional 1 COM card is a single RS232/422/485 port terminated in a standard DB9 male D-connector, on the back panel of the HX511. The optional 3 COM card is terminated in a 34-pin (0.1” spacing) male header connector on the front panel, that mates with a header connector wired up to three DB9 Male connectors, using short cables. Figure 5 is a photo of the 3 COM cable assembly. I thought I was quite familiar with header assemblies, but this one is quite unique in that it contains push pins that operate spring-loaded contacts, allowing you to insert (or remove) the wires (with ferrules) easily and repeatedly.

FIGURE 5 The three COM ports provided by the 3 COM option are terminated at a 34-pin header on the front panel. The mating plug contains 3 short cables terminated by DB9 sockets.
The three COM ports provided by the 3 COM option are terminated at a 34-pin header on the front panel. The mating plug contains 3 short cables terminated by DB9 sockets.
This is the pinout diagram for the DB9 connector used for both the 1 COM and 3 COM multi-protocol Serial cards.
This is the pinout diagram for the DB9 connector used for both the 1 COM and 3 COM multi-protocol Serial cards.
This screen capture of Device Manager shows the COM ports present on the review HX511. There are some duplicate entries—these are explained in the text.
This screen capture of Device Manager shows the COM ports present on the review HX511. There are some duplicate entries—these are explained in the text.

It’s been years since I dealt with RS232 ports on personal computers, modems, and so forth. However, I still recall that the “standard” pinout on a DB9 connector (as well as its gender) depended upon whether the unit was defined as Data Terminal Equipment or Data Communication Equipment. So, any confusion in this regard is removed by referring to the DB9 pinout diagram shown in Figure 6Table 3 defines the pin definitions when the port is configured in either RS-422 or RS-485 mode. Note that in RS-232 mode, a full set of hardware handshake lines are implemented.

This table defines the pin definitions when the port is configured in RS-232, RS-422 or RS-485 mode.
This table defines the pin definitions when the port is configured in RS-232, RS-422 or RS-485 mode.

Figure 7 is a screen capture of the Device Manager utility showing the COM ports. The HX511 review unit contained both a 1 COM and a 3 COM option card. The COM1 Communications Port corresponded to the 1 COM board (DB9 on the back panel) and COMs 2, 3, and 4 corresponded to the 3 COM board, terminated on the front 34-pin header connector. I suspect that this COM port designation is constant whether or not you ordered the 1 COM board—that is, if you only ordered the 3 COM card. The reason I believe this is as follows.

The BIOS section corresponding to the COM ports is titled “Advanced > SIO NCT5124D.” This is a bit cryptic, until you realize that the NCT5124D refers to a Nuvoton NCT5124D device. This device contains four UARTs, each with 128-byte FIFO buffers on transmit and receive. It contains the RS-232 hardware handshake lines as well as Auto Flow control for the RS-485 mode. It interfaces to the Intel processor using the eSPI bus interface, which is an enhanced Serial Peripheral Interface developed by Intel. The NCT5124D is labeled as the SIO block in section “1.5 – System Block Diagram” in the HX511 Product Manual. The NCT5124 chip is always mounted on the HX511’s motherboard and ordering either the 1 COM or the 3 COM options just adds the proper cables and termination socket(s) to the unit.

The easiest way to check out the COM ports is to load the PuTTY terminal emulator program (or another serial terminal program like RealTerm). A link to PuTTY is given on the Onlogic site [2].

I just used a DB9 female connector with pins 2 and 3 jumpered together (Rx, Tx lines). Running PuTTY and selecting each COM port in sequence, I could see that whatever I was typing into the terminal window got echoed back and was displayed. Connecting my scope to a COM port Tx line, I was able to determine that the port’s baud rate could be changed from an application (for example, PuTTY) and not only from the BIOS COM port configuration menu. From the factory, all COM ports were configured for ±5V levels, but ±12V is also available through the BIOS.

Figure 8 is the COM port configuration screen in the BIOS. Please excuse the camera image—the normal Print Screen procedure that works with other BIOSs does not work with the InsydeH2O BIOS. The Base I/O Address and Interrupt are set to normal PC defaults and shouldn’t be changed. The Peripheral Type is where you select either RS-232 or RS-485. There are four available settings for the NCT5124D’s master clock: 1.8462, 2, 24 and 14.769MHz. You should be able to generate even non-standard baud rates using one of these selections.

The Mode Selection option shows the different variations of RS-485 and RS-422 that are available. I picked RS-485 Half Duplex (terminated) for a quick test. Figure 9 shows a capture of my scope, with TX+ on channel 1 and TX- on channel 2 (and a 120Ω terminator in place). This shows the standard RS-485 differential signal with an amplitude of 2V on each channel, or 4V total. I was expecting both the TX+ and TX- to be sitting at a static level of 2.4V, from past experience. Here, however, TX+ was sitting at 2.0V and TX- was lower, at 1.58V. I don’t know if this is too meaningful, as it’s the differential signal levels that are being used.


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This is a photo of the BIOS screen used to configure the COM ports.
This is a photo of the BIOS screen used to configure the COM ports.
This is a scope capture of one of the COM ports, in RS-485 mode. This shows the differential Transmit signals.
This is a scope capture of one of the COM ports, in RS-485 mode. This shows the differential Transmit signals.

There is a power enable option available for the COM ports. What this does is provide power to pin 9 of the DB9 connector in RS-232, RS-422 or RS-485 modes. The Power Select option selects the RS-232 signal levels and also affects what voltage is available on pin 9. I haven’t seen in the documents how much power is available using this feature. I would guess it is enough to power a small RS-485 sensor, for example.

There are quite a few different modes of operation among the three main serial protocols shown in Figure 8 (the BIOS screen photo). These are not described in any of the HX511 documentation that I can find on their website. However, when I opened the HX511 case and examined the 3 COM board, I found that it contained two F81439AN chips. These are programmable multi-protocol transceivers, made by Fintek, that provide the various RS-232/422/485 signals, as configured in the BIOS. This information can be found in the datasheet for this device [3].

As far as serial ports are concerned, just ignore the COM5 port shown in the Device Manager. It is associated with the Intel AMT. The COM4, COM6 USB Serial Devices connect to an iMX1050 MCU on the DIO card—it acts as a co-processor for the optically-isolated digital inputs and outputs contained on the DIO card. Also ignore the duplicate entries for COM3 and COM4—these are explained in the next section.


Whereas the NCT5124D’s quad UARTs are directly interfaced to the Intel processor using the eSPI port, the DIO ports are not. The I/O pins themselves are optically isolated from the rest of the HX511’s circuitry, of course. What I mean here is that the DIO ports are not just one parallel port for input and one for output, directly connected to one of the Intel processor’s buses.

Instead, the DIO function is implemented using an i.MX1050-series microcontroller that communicates over one of the Intel processor’s USB ports (configured as a CDC virtual COM port). Unlike the 3 COM card, the DIO circuitry is on the hidden side of the motherboard, so I couldn’t examine it closely.

OnLogic also uses the iMX1050 ARM MCU on several of its other I/O cards (the CAN card, for example). The user accesses the DIO ports using the iMX1050’s Shell command line interface. The documentation for that includes many features that apply to the other cards. Therefore, I assume that the iMX1050 firmware may be the same for the other cards.

Checking out the DIO card, I ran into some headwinds that were Windows-related, not the fault of the HX511 DIO hardware. If you refer to Figure 7, you’ll see that Windows 11 Pro enumerated the unit’s COM ports as:

  • Communication Port COM1, 2, 3, a duplicate 3, and 4
  • Intel Active Management Technology (COM5)
  • USB Serial Devices COM4 and 6

COM1-COM4 are the four UART ports associated with the 1 COM and 3 COM cards, and they all worked properly. The duplicate of COM3 is an enumeration mistake on Windows’ part. Ignoring COM5, the Intel AMT port, the only remaining ports are two USB-emulated Serial Ports—COM4 and COM6. There is only one physical USB port on the Intel processor which connects to the DIO’s iMX1050 MCU. I believe that the DIO MCU enumerates as two USB CDC COM ports, only the first of which is associated with the iMX1050’s shell monitor.

I followed the instructions for configuring the DIO, a link to which is available on Circuit Cellar’s Article Materials and Resources webpage [4]. I was unable to connect to the DIO’s shell using either COM4 or COM6. After some head scratching, I ended up uninstalling all of the COM ports, using Device Manager, and re-starting the HX511. While the new USB enumerations still contained some duplicate COM port numbers, there was a COM5 USB Serial Device in the Device Manager list that was not a duplicate of the COM1-COM4 UART ports associated with 1 COM and 3 COM. I was now able to use COM5 to connect to the DIO shell properly—that is, I got the uart~$ prompt. I suspect that other users may encounter the same anomaly. Rather than uninstalling all of the COM ports, like I did, after reporting this issue, OnLogic stated that I could have instead used the Advanced settings in Device Manager to change the port number of the first USB Serial Device in the list to a non-duplicated COM number.

Honestly, the documentation that I found for the DIO card on the OnLogic website was inadequate. After speaking to OnLogic support, the following items became clear:

  • Much of the eight pages describing the iMX1050’s MCU Shell are not applicable to the DIO card. This is likely because the same iMX1050 MCU and associated firmware are used on other OnLogic cards, with different capabilities.
  • You must refer to the DIO card as DIO0—where the last character is a zero, not an “O.” It’s easy to get this wrong as the “O” and “0” look quite similar with the font that they used. As far as I know, you can only have one DIO card in the HX511, so the zero suffix seems superfluous.
  • The VISO pin on the DIO’s 16-pin header connector is an input—you have to supply outside power (5V-48V) in order to use some of the DIO port’s features. For example, to use a simple low-side switch on the input ports, external VISO power must be applied in order to have the input pin(s) pulled high.
  • If you use the digital inputs in an Active-High mode, it’s unspecified what voltage/current is needed. Presumably, you are driving the emitter side of an optocoupler, but what is the series resistance used on the DIO board to limit the current?
  • The circuit showing a Digital Output (Low-side/Sinking) is clear enough in that it shows a current sink capacity of up to 150mA and should work with a VISO in the range of 5V-48V. However, in the dio section of the MCU shell, there is a mode command that shows options for either sourcing or sinking current. There is no explanation on whether this applies to the DIO, or what parameter would be needed to put the DIO output(s) into the source mode.
  • The dio section of the MCU Shell contains a PWM command. I don’t believe this works, as that command is rejected.

Once I became aware of the above, I was able to hook up a switch as shown in the “Digital Input (Active-Low)” example, and read the state of INPUT3 using the command:

dio get DIO0 input 3

This would return a “0” if the switch was closed and a “1” if it was open.

Placing an LED (with a current-limiting resistor) from OUT0 to VISO (powered externally with 5V), the LED would light up when I gave the command:

Dio set DIO0 0 false

This is correct: false would signify a low output—and since the LED was tied to VISO, it would light under those conditions.


I personally have no experience with the CAN bus, which originated in the automotive business. Therefore, I didn’t ask to have this card installed in the HX511 review unit. This option terminates in a DB9 socket on the rear panel, which shares the cutout that is used by the 1 COM card in the review unit. So, I assume you would have to settle for a 3 COM card if you needed both a Serial port(s) and the CAN option. Since the DIO circuitry is hidden from view (with only the bottom cover off), I am not sure if the iMX1050 MCU, associated with the DIO function, is on the motherboard and may be used to implement the CAN option as well. The documents covering the DIO’s MCU shell commands include CAN commands, so this is a distinct possibility. Whether or not both the DIO and CAN ports share an iMX1050 MCU, I suspect that the Windows enumeration issue, described in the DIO section, may apply to the CAN option as well.


The fact that the HX511 is fanless is more important than one might think. On consumer PCs, the presence of one or more fans is only somewhat annoying, because of the noise it produces. The fans used in consumer PCs are as inexpensive as possible, but the bearings will usually wear out first, and the whine will warn the user that a problem is coming. In addition, all modern PCs monitor the processor temperature and throttle it back if it starts to overheat, thus preventing at least a CPU failure.

In an industrial setting, the manufacturer could choose to spare no expense and provide the best quality AC mains-powered fans in their computer. During my career maintaining complex instruments in a university setting, many such instruments contained fans that ran 24/7 and lasted up to 10 years. However, even in that relatively clean environment, the high airflow that these fans produced meant that dust and grime would have coated the electronic circuitry, causing problems, had filters not been used. In an industrial environment, the air quality could easily dictate that such filters be changed frequently. This takes manpower, and if neglected, a plugged filter is just as bad as a stalled fan, in terms of a possible equipment malfunction. This is probably the main reason to choose a fanless computer like the HX511.

Since the HX511 is fanless, there is no way to speed up a cooling fan(s) if the unit’s processor is working hard (Turbo mode) or if the ambient room temperature rises. Similarly, if it’s embedded in a larger unit, how will it work if that interior temperature rises too far above ambient? In the HX511, this is addressed in the following ways:

  • The lower TDP versions of Intel’s processor are used (Hybrid models—ending in the HL suffix).
  • The case is a massive heatsink, capable of dissipating a lot of heat.
  • All heat-producing chips and modules on the motherboard are placed in such a way that they can be thermally coupled to the heatsink/case.

The HX511’s case and motherboard are the same regardless of what customer-selected options are selected, including processor type. It follows that it must be designed to run with the most powerful processor (i7) as well as a unit with all of the IO modules present. So, for all the lower models in the line, there will be some extra margin when it comes to thermal dissipation capability.


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The HX511 is rated for operation in an ambient air temperature range of 0°C to 50°C. The results of OnLogic’s thermal testing can be found in section 5.4.2 of the Product Manual. Figure 10 shows a graph of this testing. The graph is somewhat hard to follow, since the Product Manual’s graph labels and legends are quite small and will be even smaller when printed here. But, I’ll try to explain it clearly. Throughout the testing, the HX511 (using an i7-12800HL processor with 45W TDP) is running software designed to stress the system, using a rigorous, constant workload. The six colored regions making up the X-axis denote ambient temperatures between 0°C and 50°C, controlled by a thermal chamber. Each section is two hours long.

The gray trace (upper) is the average clock speed (in MHz) for the processor’s P cores (i7 Performance cores). You can see this drops from 4200MHz gradually down to about 3300MHz as the thermal chamber ramps up from 0°C to 50°C. The brown trace (middle) is the same measurement except that the E core’s clock speed is measured (i7 Efficiency cores). The green trace (lower) is the CPU Package temperature. As you can see, this rises from about 60°C (at 0°C chamber temperature) to about 95°C (at 50°C chamber temperature). The blue trace is just a straight line indicating that the processor’s base speed is fixed at 2400 MHz throughout the test.

This is a graph showing the results of OnLogic’s thermal testing on the HX511. The labels/legends are too small, but the results are explained in the text.
This is a graph showing the results of OnLogic’s thermal testing on the HX511. The labels/legends are too small, but the results are explained in the text.
This is a thermal camera shot that I took of the top of the HX511, after running for two hours in Windows, idle mode. Note the lack of any hot spots, indicating excellent thermal bonding of the heat-producing components to the large heatsink.
This is a thermal camera shot that I took of the top of the HX511, after running for two hours in Windows, idle mode. Note the lack of any hot spots, indicating excellent thermal bonding of the heat-producing components to the large heatsink.

While I am not equipped to do such testing, I thought it useful to take an image of the top panel/heatsink after the HX511 had been on for a few hours. In this case, it’s running Windows 11 Pro, but just in idle mode. You can see from Figure 11 that the case/heatsink surface temperature is 42.4°C and is evenly distributed over the whole top cover/heatsink area. This leads me to believe that the thermal coupling, between the processor and any other major heat-producing components on this side of the motherboard, is very good.

The HX511’s bottom cover is easy to remove and exposes all of the readily changeable modules (memory, SSDs, Wi-Fi card, cellular card, and 3 COM card). Most of these are thermally coupled to the bottom cover. The Intel processor, as well as the switching regulators, are on the other side of the motherboard. The processor is carefully thermally coupled to the heatsink that forms the top cover. OnLogic doesn’t recommend removing the motherboard to view this processor/heatsink interface, and I didn’t attempt it. However, the thermal image in Figure 11 makes clear that an efficient heat transfer is taking place here, or there would be hot spot(s) showing—like you would see if you tried to take a thermal image on a high-end cell phone.


From the moment I fetched the OnLogic parcel on my front doorstep, I knew it was going to be a substantial unit. The box weighed 10 pounds—a mini-PC that I had recently reviewed couldn’t have weighed much more than one pound, even though it had about the same processor, memory, and so on. Besides being fanless, the case appears to be well-sealed, so there’s little chance of ingress of air or moisture. If you don’t order all of the IO port options, there is an option for a blocking kit that will cover up any unused cutouts.

Since I asked for the review unit to have Windows 11 Pro loaded, I didn’t have an opportunity to work with the HX511 in the Ubunto Linux environment.

On the few occasions that I needed some technical support, my email requests were met with prompt and helpful replies. In response to one email message, I quickly received a phone call from Jenna, part of the technical support staff. I almost ignored that call (not recognizing the phone number) since I’ve never gotten a phone call from tech support in response to an email before.

The HX511 is covered by a standard two-year warranty. You can extend this to five years for about $300. So, you’re getting a three-year service contract for $300. This works out to less than 4% of the unit’s cost/year, which is reasonable and reflects the expected reliability of the unit. While I no longer get involved with regulatory compliance issues, these details are all described in Appendix E of the Product Manual.

I’d like to thank OnLogic’s Darek Fanton, who handled the configuration of the review unit, the logistics, and any questions that I had that weren’t completely technical in nature. OnLogic’s products can be found on their website. 

[1] OnLogic HX511 BIOS Manual:
[2] PuTTY link via OnLogic:
[3] Fintek F81438 Datasheet:
[4] HX511 Connection Diagrams:

OnLogic |


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Brian Millier runs Computer Interface Consultants. He was an instrumentation engineer in the Department of Chemistry at Dalhousie University (Halifax, NS, Canada) for 29 years.

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The Helix 511

by Brian Millier time to read: 29 min