Hello again! Im here looking for advice on what might be preventing one energy metering from communicating its data, while two other energy meterings on the same RJS 485 cable communicate just fine. The non-communicative energy meter is a different model, being a hager HGR43-D, while the two working ones are hager HGR41-EWC. When I request data from them on Open Modscan (ID 2 & 3), I get normal results, and I can see on the energy meter screens that the symbol representing communication flashes. However, when I try to do the same with the third energy metering, (ID 1) it flat out refuses to connect. I've double checked the connection settings, changed the addresses to get any data, and nothing seems to work. The meter 1 screen shows useful data being collected and displayed, but the arrows that show when messages are sent/received via modbus doesn't appear.


The only things I can think of, besides different models, that might explain this is that the 1st energy meter is the furthest away, but its only by a 1-2 extra meters of cable, at a total of 23 meters.
Do you guys have any ideas on what I could try, what to test, that would give me more information to work with? I've already emailed Hager, to no response, and Id like to try something and get more info before emailing the manufacturer Rayleigh Instruments.

 

Does the bad boy meter have the Modbus RTU option installed?

Is the Modbus RTU option enabled?

Is the polarity [(+)/(-) or A/B Labeling] of the RS-485 driver lines the same on the different models, or did the polarity get reversed in the model change?

Did the wiring get reversed from the meter feeding the RS-485 comm cable to the bad boy meter?

You've actually checked, not assumed, that the serial comm settings are the correct settings, baud rate: stop bit, parity?

You've checked that the slave node ID address (Device ID) on the bad boy is 1?

 

Adding some additional comments to the previous suggestions.

Did you power cycle the meter after making changes to the settings? Many devices need to be power cycled for communication setting changes to take effect.

Try isolating the problem meter and test communications by disconnecting it from the other meters' RS-485 bus and directly wiring it to your laptop's USB to RS-485 adapter.

How many conductors are you using for your RS-485 wiring? If only 2 (used for + and -), try adding a 3rd wire for the 0V reference (assuming the meters have a 0V ground reference terminal or pin).

 

What jschulze said about adding a 3rd conductor (gnd) is a good one. You have already a pretty long cable. Did you terminate the end of the cable with a 120ohm resistor between the A and B line of the modbus?

Since you already have a pretty long cable with 23 meters you could try using a proper impedance corrected cable, like the Lapp Unitronic bus LD cable. This cable is 120ohm impedance corrected and therefore keeps your signals going into the cable the same as where they come out.

At Conrad you can order them per meter. I always use this one with great success: https://www.conrad.com/en/p/lapp-21...2-x-0-22-mm-violet-sold-per-metre-600618.html

Use the white/brown for A and B (since white/brown are twisted inside the cable). And use the green for the GND signal.

Good luck and keep us posted on the developments.

 

The electricians used ChatGPT for instructions on wiring the RJ25 cables and mixed up the pins .....
All is fixed now that the pins are in the proper position according to the manual!

 

Hahaha!
The joke of the month......using ChatGPT for technical information..........
Looking forward to the next one that makes the same mistake!