Relay Board cannot establish connection through RS232


My company recently ordered a second Industrial Relay Controller 32-Channel (Part Number: ZADSR32xDPDTPROXR Rev. C; found at this link: to replicate an existing system we had made a few years ago, which utilizes the exact same Relay Board. We communicate through the ZRS-AB 3-Wire DB-9 Interface, and we use an in-house software to send the commands to the relay.

This communications link works fine with the first board, but it is unable to establish a connection with this new board. In an effort to troubleshoot, I installed the Base Station software to see if I would be able to communicate with the new board in this way. After selecting the communications port (COM1), the Base Station software then searches through all the baud rates, but it is unable to communicate and then closes.

The red PWR LED on the ZRS-AB breakout board is illuminated, and I have confirmed the continuity of the connection from the 3 terminals on the breakout board all the way to the DB9 plug going into the PC. Additionally, the first red LED in the 10-LED bank is on for relay Banks 2, 3, and 4, but not for Bank 1 (this is the same case with the functioning first board). However, when trying to establish connection through the Base Software, this first LED for Bank 1 flickers. Lastly, I am running Base Station on Windows 7, which I know is not a tested OS and could therefore be a source of error, but the first board is commanded by a Windows 7 OS with no issues.

Any thoughts about what I could be doing wrong, or what could be wrong with the board? Prompt reply would be appreciated, I would also be happy to set up a call to discuss this issue.

Thank you,
Bryan Davis

The first LED on bank 1 is the Rx LED which will flash whenever the board receives data. The second LED on bank 1 is the Tx LED which will flash whenever the board sends data. It sounds like the board is receiving data from Base Station but is unresponsive as it is not sending anything back.

One thing you could try is pulling the ZRS module out of your first board and install it in the new board. Test and see if that works. If not then try swapping the Pic Chips between the boards. Just make sure they both say Pic18F14K22. If the first board is a Pic16F690 then it will not work in the old board because it is an old ProXR Standard board. If it is an old ProXR standard board please let me know. Lastly make sure the power supply you are using with the new board is good(you can use the power supply from your first board to make certain).

If none of that isolates the problem then I can’t really think of anything else which could be wrong. In that case I would recommend returning that board back here for testing/repair. Just ship it to:

National Control Devices
430 Market St
Osceola Mo, 64776

In the shipment include a written description of the problem(your description above should be fine) along with your contact information and return shipping address. Repairs are generally processed within 2-3 business days.

Thank you Bryan,
Travis Elliott

Hi Travis,

Thanks for your quick reply. Both boards are PIC18F14K22, so no issue there. I will have to grab the first board from another one of our facilities, but I will run all of your suggested tests and let you know the outcome.

Thank you!

Great. Let me know what you find.

Hi Travis,

As you suggested, I pulled the ZRS module out of my first board and installed it in my new board, and everything worked fine! I was able to establish a connection through the Base Station software and control all the relays.

Comparing the two ZRS modules, they look exactly the same and appear to be the same model, although the newer one (the non-functioning one) has some imperfections on the bottom face that may or may not have an effect. Regardless, it looks like we’ll need a new ZRS-AB module to get our new system working. Can NCD provide a new module? We can ship the non-functioning module back for repair, but due to time constraints, we would prefer a new module in the meantime to get our system up and running. Let me know what you can do!

Thank you,

Hi Bryan,

You do not need to return the old module. We can ship you a new one. Send an email to DeeAnn in shipping/accounting, her email address is Let her know I pre authorized shipping you a new ZRS-AB module at no charge as a replacement for a faulty one you received. She should be able to get that out to you in the next day or two.

Hi Travis,

Great, will do! Thanks so much for all your help!