Schneider PM800 issues

J

Thread Starter

JFX

Hello all. I'm having issues communicating with Schneider PM800 meters. Protocol is Modbus RTU, unit address is '001', baud is 9600, parity is 'none', Cat6 comm. line is wired and terminated (no ground though) to 3 daisy-chained remote-display meters. Modbus/SNMP bridge talks but I only receive errors and/or '0' for data from meters that have load indicated. I've tried both Integer and Floating Point, 1, 2 and 3 meters, Comm 1 and Comm 2 but nothing.

I'm out of ideas. If anyone has any experience with these I'd appreciate any suggestions.

Thanks in advance.
 
No experience with PM800, lots with Modbus, so curious

a) why "Cat6 comm. line is wired and terminated (no ground though)" but you mention serial "Modbus RTU".

Cat6 is normally associated with ethernet. A quick look at Schneider's site shows that the PM8ECC ethernet module is optional. Are doing Modbus RTU over serial (RS-485?) or Modbus TCP over ethernet? Or do these PM800's use RJ-45 and CATx cable for serial?

b) Are these multiple PM800's on the workbench or spread out over a large area?

c) Which Modbus master are you using? SCADA/HMI or a tester like Modscan32?

d) Have you tried even parity? 'No parity' can be touchy, one or two stop bits, depending.

e) Does the master have native RS-485 ? or are you using 232-485 adapter

f) I'm too ignorant to know what "Modbus/SNMP bridge" is. What's that?

g) Have you limited Modbus to a single device, without the issues of multi-drops ?
 
John you said "I'm too ignorant to know what "Modbus/SNMP bridge" is. What's that?"

I think its a simple gateway babel buster SPX or maybe any other gateway.
 
FieldServer has connected to a PM800 many times in the past with Modbus RTU RS-485, from there many other connections can be used including SNMP,BACnet, LonWorks ... try the QuickServer it works very well in this application.
 
Sorry for the late reply, I've been away for a number of weeks.

a) I'm just using Cat6 as 2-wire. There's no Ethernet modules installed.

b) The meters are in a remote MCC across a room from where I have other monitoring terminations. I have Cat6 in conduit to a patch panel area from the meters. We installed Cat6 just as comm wire.

c) I'm trying to use a IB-110 bridge. Same maker as babel buster.

d) I've tried two testers (serial) that Schneider sent me. No response from either. According to the meter doc, pinouts are 2, 3 and 5. I'm confused why the tester is Serial and by bridge is not. I think the light just went on over my head. See below. Remember I know not much about Serial, have been doing Modbus to SNMP for about a year with other devices.

e) Not using an adapter. Meters are selectable, 232/485.

f) Bridge is the IB-100 modbus/snmp bridge converter device.

g) Today I removed all other meter connections so I just have one meter in case it was multiple meter issues. Also grounded it. Was using no parity, might try even or odd.

I think it just dawned on me from your response above - Modbus RTU is serial no? So these can't be directly connected to the IB-110 modbus contacts? If not, our Eng. spec'd the wrong meter for the application. I have other Modbus devices to monitor that are not serial. Perhaps the Ethernet module would be the best way to go now, I have 7 meters that I can't talk to.

Thanks to all for the help.
 
I hope you have different meter IDs in all the meters & not 001 in all of them.

What is the error code you are receiving from the Modbus transactions, if any?
 
> What is the error code you are receiving from the Modbus transactions, if any?

IB-100 is 485 RTU native and the meters are selectable, set to 485.

Meter unit numbers are set.

To remove variables, I rewired so only one meter is on the twisted pair line - unit 1, line is grounded and terminated with an end-of-line resistor.

Error code is '5/0' from the IB-110 - 'no response'. Requesting 1100 as holding register, integer and 11700 as floating point. Noted a reference in the doc to a 30,000 or 40,000 offset in register numbers that 'can be used'. Also tried to read 31100, 41100 then as both integer and floating point. Still no responses.
 
Couple of pointers for you:-

1. You are using PM8RDA remote display adapter which has a selectable RS232/485 interface [you selected RS485] & 2wire/4wire interface. I hope you have put the jumpers [TX+:RX+ & TX-:RX-]. Also try reversing the polarity of the wires.

2. You are configuring 2 Modbus queries - 1 for 1100, 1 for 11700. Have you configured any delay in the IB-100 to listen after TX? For testing configure only 1 command.

3. Register 11700 contains a floating point value so you will have to request 2 registers starting from 11700. Of course if the IB-100 sends request for 2 registers by itself, then this point is moot.
 
1. Correct on the display adapter. I have selected 485 as the IB-110 is 485 native. I have jumpered the 4-wire connector as I'm using 2-wire connection to the Bridge.

2. I don't know how to program a delay but can look into how to do it. I have tried one command and several, no response to either.

3. Understood that a floating point register is double. The IB-110 looks after this. I have tried 'doubles swapped' and not. I did the manual register entries to enable the floating point registers. I can display 11700 on the display with the diag function and it displays data.

I get 5/0 'no response' errors regardless.

I'm starting to think either the Bridge or the PM8RDA adapters might be toast, nothing works.
 
Andrzej: Downloaded it yesterday. Thanks for the tip. I have an old clunker laptop w a 9-pin serial port I'll test with today. Initial tests with USB to serial adapter on current laptop to the meter failed, I couldn't get the laptop to release the ports in use.

 
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