No communication Fieldpoint RS485 Network Module FP1001

[GeneralKen]

Network module reports back "timeout error"

Cannot even reset the module.  Get "timeout error" on reset or changing any paramter.

Set baud rate to low value of 1200 baud but still no success.

There are two FP1001 modules on the RS485 bus.  One of the modules seeems to work OK. It has a single analog output module that I can write to.

The other FP1001 module has 8 x FP-TC-120 modules and I cannot get a reading from any of them.

This equipment had worked for 2 years.

What test can I do to verify that the FP1001 module has failed.  It seems to have all the correct blinking lights when I power it up.  What am I missing?

Ken Gruhl

kggruhl@griffithenergyproject.com

Tel:  928-718-0102  X226

[Aaron_G]

Ken,

The timeout response indicates that no message was received back from the network module. This is most commonly due to incorrect wiring or communication settings (e.g. wrong baud rate). Thus, a reset will typically not work. Since one of your FP-1001's is responding and the other isn't, I would check how they are both wired (computer Tx+ should be wired to Rx+ of both FP-1001s, computer Tx- to Rx- of both FP-1001s, computer Rx+ to Tx+ of both FP-1001s, and computer Rx- to Tx- of both FP-1001s). Check that the RS-485 connector is firmly inserted into the module, that the biasing resistors have not been damaged, and that you have full wiring connectivity. You could swap the two FP-1001s to see if the problem follows the FP-1001 or remains in the same position. Also, make sure that both FP-1001's have been set to the same baud rate but different addresses via the dip switches. If you change the baud rate or address via the dip switches, you MUST cycle power to the FP-1001 for the new settings to take effect.

When troubleshooting communications, you can look at the Network and Access LEDs. Network indicates that there is serial port activity on the RS-485 bus, but not necessarily directed at the specific FP-1001 (or attached modules). The Access LED indicates serial activity that has specifically addressed the FP-1001 or its attached IO modules.

Regards,
Aaron

[GeneralKen]

This morning I interchanged the FP1001 Network Modules and check addressing and baud rates.  The timeout problem did not move.  All symtoms remain the same.  Cannot talk to the remote module containing the FP-TC-120 themocouple modules.

Please advise.

[Aaron_G]

Ken,

Since the problem remains in the same spot, I would check:

1. The Network and Access LEDs and described in my previous post (preferably while MAX is active and trying to communicate with the modules).
2. The power supply to the network module.
3. The serial cable between the two network modules.
4. The biasing resistors on the serial cable.
5. The end connector on the last terminal base to make sure no metal pieces have gotten in it (assumes that the protective end cap that ships with the network module was not installed).

Regards,

Aaron

[GeneralKen]

Yesterday I had someone watch the Network and Access lights on the FP1001 module while I was writing to it.

No activity on the FP1001 lights.

Checked cable.  5 ohms measured between all wires.  I believe the cable is shorted, and will check it out today or tomorrow.

It is amazing that the local Network module worked at all.

I am quite sure the problem is a shorted cable.  Will let you know the results.