ABB Drives and Modbus

Hey everyone. I'm thinking of taking the plunge. Typically when I do VFD/PLC based applications, they have been hardwired. As you know this can be a lot of wiring if you're using and getting as much out of the drive as you can. The ABB ACS550 has built in Modbus. I have tested many times at my desk, interfacing to the drives from a PLC via Modbus. Seems to work just fine.

My thoughts are, it doesn't get much more reliable than hardwire, so why swith away? Well, I can get a lot more analog and digital parameters out of the drives if I use Modbus. I'm really concerned about the reliability.

I have used Modbus extensively for chart recorders with great success. We use DeviceNet and other protocols extensively in our plant for drives.

I'm just curious if anyone has experience with using the on-board Modbus feature with the ABB drives. Can someone tell me how robust it is? (Assuming good wiring practices, etc...)

TIA,

Greg

experience:
I, too, have had excellent reliabilty with recorders; PLC to recorder and recorder to HMI.

Although I have no ABB drive experience, their excellent reputation must infer a solid Com port.

I can recommend investing in RS-485 isolator(s). Isolators have saved the CRU Com port and other ports on the bus more times than I care to admit. If I have 6 drops on the 485 bus, I'll protect the CPU with one isolator and split the bus 3 and 3 with the other isolator.

Dan

For isolation I normally use the Adam 4520 232/422-485 converter. These are 24VDC powered and work extremely well. Can be used as extenders also. Available fro Advantech.

I have seen some not so good reports on ABB drives on Device Net. The EDS files appear to be a bit "flakey". Have had problems with this in the past. No experience with them with Modbus though.

Thanks for the info guys. So you isolate between the PLC and the recorder? I use RS-422, I haven't had the need to isolate yet. If I'm doing the drives perhaps I should?

Bob, the ABB DeviceNet is ABSOLUTELY horrible. I integrate 550's and 800's in our plant and have tried the DeviceNet module for them. Yes, the EDS files are flakey. The expanded EDS file absolutely does not work, only the standard profile works. Lucky for ABB their drives are good, the DeviceNet experience was soo poor it would have made me switch away from ABB drives. Tech support was entirely useless with these modules. I've been eyeing up the Ethernet modules for the 550's, they look a little better, but I'm not going to be the first to try them. Any takers?

Greg

Hi


I have very good experience with ABB with modbus.
I used ACS880 160KW and 200KW also with ACS550.
If you have HMI in your system you can use Hakko they have build in port which you can use for modbus.
I use it every time instead analog I/O.
Use harware for run/enable and write sequence to check the communiction .if you have com fault stop the driver.