Replacing Freq Drive brand on ModBus

Rob S.

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Join Date
Sep 2008
Location
Maryland
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739
Good Afternoon ,

We are doing a small upgrade on a certain portion of a machine but I would like to keep the Modbus network. I would like to replace 2 Schneider ATV312H075N4 Drives with AC Tech Drives. We are communicating with Modbus . How difficult is it to replace a drive with a different brand on a Modbus network.
It cannot be has easy as making the Modbus address the same on the AC Tech drive as is on the Schneider ATV312H075N4, is it ? I'm sorry , I am just not too familiar with Modbus like I should.

Thanks in advance,
 
No, it's not that easy, but it's not too difficult either if you have any communication string programming capabilities.

First obtain a "Modbus Register Map" for both drives. Then look at your PLC program for where it accesses the drive via a comm command, and look at the Modbus communication packet that each command is currently utilizing for the ATV drive. Each command will be in the form of a packet of data conforming to the Modbus standard format, and buried in that packet will be the register address within the device (not the NETWORK address) and the bit value(s) that gives the drive the command(s) it needs. Using the map, determine what that register and bit value corresponds to in the drive programming, then find the matching register and functions in the AC Tech drive. Replace the ATV register number and necessary bit values with the AC Tech register and bit values number in each command in your PLC code.

You may also need to double check the packet format to make sure they match. Modbus command packet formats are SUPPOSED to all look the same, but sometimes they are tweaked by manufacturers, and that only ends up being an issue when you try to do something like this.

If all of this looks Greek to you, consider farming this out to a pro.
 
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If I replace the Schneider ATV312H075N4 Drives was the Altivar 31 Drive , with Modbus , if I set it up with the same address and other parameters it should run the same , correct ?
 
You will actually have to read manuals and compare the the Modbus locations of information in the two drives. It is very unlikely that they will have precisely the same information in the same location.
 
You will actually have to read manuals and compare the the Modbus locations of information in the two drives. It is very unlikely that they will have precisely the same information in the same location.

If you don't want to read the manuals, you can ask Schneider Electric for help.
 

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