Quick Take
The decision here is about interface and condition as much as price. The NCD.io PR55-36_9HP is the only full edge computer in this group, with a 900MHz radio, WiFi, and a populated SIM slot, but it also carries the highest price at $375.00. The Apex Industrial Tech 31-04115-08 is a new open-box PCB with a clear model and MPN, priced at $199.99. The PLC C515RA amplifier card is a DIN 41612 module for older rack systems, listed at $150.00. The ST4504-2 control board is the least expensive way in at $99.99, with CE marking and a gold edge connector.
Listed-Price Comparison
| Product | Listed Price | Price Bar |
|---|---|---|
| NCD.io PR55-36_9HP Industrial IoT Edge Computer | USD 375.00 | |
| Apex Industrial Tech 31-04115-08 Edge Variants PCB Control Board | USD 199.99 | |
| PLC Industrial Control PCB - A1 Final Amplifier Card C515RA - DIN 41612 | USD 150.00 | |
| ST4504-2 Industrial Control Board - CE Marked - Gold Edge Connector | USD 99.99 |
Decision Matrix
| If you need... | Product | Why it fits |
|---|---|---|
| A long-range wireless edge gateway | NCD.io PR55-36_9HP | Includes 900MHz XBee, WiFi, Ethernet, USB ports, and a populated SIM slot. |
| A new open-box PCB with a stated model and MPN | Apex Industrial Tech 31-04115-08 | New open-box board with model and MPN clearly listed. |
| A vintage DIN 41612 amplifier card | PLC Industrial Control PCB C515RA | Rack-mounted amplifier PCB with DIN 41612 connector and trim potentiometers. |
| A used control board with CE marking and a gold edge connector | ST4504-2 Industrial Control Board | Used board with CE marking and a gold edge connector. |
Product Notes
NCD.io PR55-36_9HP Industrial IoT Edge Computer XBee 900MHz WiFi LTE SIM Populat
This is the only full edge computer in this group. It comes with a Digi XBee PRO S3B 900MHz radio, an Onion Omega2S+ module with WiFi, OLED display, Ethernet, SD card slot, USB-A and USB-Mini ports, and a populated SIM card slot. The unit is new and never used in production, with the power adapter and both antennas included. It does not come with the original box or documentation, and the software may need a factory reset. This makes it a good fit for someone comfortable with a little setup before deploying it in an IoT edge control project.
Apex Industrial Tech 31-04115-08 Edge Variants PCB Control Board 30-04376-02
This PCB control board is the clearest match if you want a named manufacturer and a concrete model reference. The board is identified as Apex Industrial Technologies, model 31-04115-08, with MPN 30-04376-02, so you have something specific to cross-reference. It is new open-box, meaning the packaging has been opened but the board itself has not been put into service. The edge-variant PCB design implies it is meant for a particular OEM system, so the board's overall fit depends on the edge connector layout and the rest of your control stack.
ST4504-2 Industrial Control Board - CE Marked - Gold Edge Connector
If the goal is simply to get a usable industrial control board without spending for a new unit, this used board is the one. It has a gold-finger edge connector and is labeled with the ST4504-2 identifier and CE marking. There are green jumper wires on the board that indicate field modification or repair, so treat the board as service history rather than pristine factory hardware. It appears to be a general OEM control board for automation equipment or legacy machine controllers. This is the option to consider when you need used hardware and can accept visible modifications.
PLC Industrial Control PCB - A1 Final Amplifier Card C515RA - DIN 41612
For anyone maintaining or restoring older rack-based control systems, this is a specific amplifier module. It is labeled A1 Final Amplifier with PCB marking C515RA and connects through a DIN 41612 backplane edge connector. The board is clean, with no visible damage, corrosion, or burned components, and it comes with red card ejector handles and multiple trim potentiometers for calibration. It is listed as used and untested, and it carries an ESD-sensitive marking. Treat it as a module that will need inspection before being energized in a system.
Final Recommendation
- For a complete edge computer with long-range wireless and cellular SIM support: NCD.io PR55-36_9HP.
- For a new open-box PCB with a clear model and MPN: Apex Industrial Tech 31-04115-08.
- For a vintage DIN 41612 amplifier card in a rack system: PLC C515RA.
- For the lowest listed price on a used control board: ST4504-2.
Consider the condition and interface first. If your controls are modern and wireless, the NCD.io unit covers the full edge-computer feature set. If you need a specific module for an older rack, the C515RA is the only DIN 41612 option here. For lower-cost replacements, the ST4504-2 is the entry point, while the Apex board gives you a concrete model to match.
