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Modbus from V570 to Altivar 312


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Hey All,

I have a little retro project going on that involves Modbus control of some Schneider Altivar 312 VFD's.

I have done a couple of projects using Modbus with A-B Powerflex VFD's and that all went well.
I don't have a lot of experience with the Altivar 312 VFD's, and I'm not having much luck finding the info (I think) I need.

The A-B user manual clearly states the register addresses and values for the different Modbus functions;

Logic commands get written into "8192"
speed commands get written into "8193"
logic status is read from "8448"
faults are read from "8449"

But, I can't seem to find this same info for the Altivar VFD's,
the user manual talks about Modbus control, but then directs you to a Modbus manual which gives info on RS485 connections and Comm settings.
but I dont see just a simple list of register address and values....

Like I said, I have limited experience with it, but I was under the impression that Modbus was a universal thing, and had hoped that the register addressing was the same (aside from a register offset depending on whether a system is 0-based or 1-based).

Can anyone confirm or deny my thinking?
Can anyone point me to a list of register addresses and such for the Altivar VFD's?

Regards,
JohnR

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that's kinda where I was at.

000F for run

but I thought 0007 for the stop.....

 

but I still can't get it to work......

 

communication seems okay, at least it appears to.... the status messages come back "0"

I sequence through my modbus logic with an index that advances upon the completion of the previous call....

 

I've done identical logic (with the exception of different register address and cmd values) with A-B powerflex VFD's and it always works, something I'm missing, just not sure what.....

 

JohnR

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Gabriel,

 

thanks again for the input, I previously was reading the speed feedback (3202), and fault register (3250)

I changed from the fault to the status word (3201), and I get back 576 (dec) which converts to 1001000000 (bin)

which I read as ;

bit 6 - switch on disabled

bit 9 - forced local mode (active at 0)

 

What I'm working on is a small machine that our company acquired, it has 6 VFD's with little more than run logic and speed commands.

The VFD's are currently being controlled via Modbus by a Schneider Twido PLC/Majelis HMI, which I have no documentation or software for.....

So I am trying to replace the controls with a V570 to make it user friendly for me.....

 

I can make the VFD's run from the Schneider controls so I know they work, perhaps I'm missing some command I need to make them run from my Unitronics platform.

Again, I have very little experience with the Ativar VFD.....

 

JohnR

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Hey All,

 

thanks for everyone's input,

 

after a week of banging my head against the wall, I finally did what I should have from the start.

 

I took out the Schneider VFDs and put in Allen-Bradley VFDs,

 

3 simple parameter changes and I'm running Modbus........

 

regards

JohnR

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Didn't realize you were using multiple Drives. Something I have found when using the ATV212 or ATV312 Drives with Modbus/RTU is that all the Drives have to be set Line Termination instead of the just the PLC and last Drive in the piggy tail series. I typically use 2-4 in an installation and if I do just the PLC and last Drive it doesn't work. If I do all 2-4 Drives it works.

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