NB5 & Modbus

[lostcontrol 23]

Hi I am testing the NB as a modbus master with mixed results. It seems I am able to write to the salve device, but not read correctly. I switched to just using multiway, & all appears correct when monitoring the send/recv strings, but the value on the NB does not update & a comm error is displayed. I am pretty sure I have the wiring correct, using 485 from pins 6&8 through a 485/232 converter to multiway. Any suggestions on where I might be going wrong?

[ParaffinPower 13]

Hi lc I've used the NB as a modbus master a few times with MX2 inverters. Whilst testing I just had the Comms wiring thrown at it on my desk and saw exactly the same results as you. I changed to proper screened twisted pair and it worked perfectly. The message obviously 'got through' to write, but the NB couldn't interpret the reply. Pp

[lostcontrol 23]

Hi PP, The cable was in my list of things that cod be a problem, but since I have used this same wiring & environment with a Magelis testing the same thing, I put it to the bottom of list. I am going to try the NB as a slave to see if that makes any difference, but is wierd that multiway receives/replies as expected, yet the NB reports timeout