Bizarre ACH550 VFD Control Situation.

[TwoBlocked]

We will have another go at this Monday, but thought you fine folks would be interested. Got an ABB ACH550 that is being switched from hard wire to RS-485/Modbus control as part of a PLC upgrade. I've been doing the wiring while a gal is doing the programming, but we help each other out.

Soooo, comes commissioning time and we are trying to get the VFD to run with the help of tech support (This parameter, that parameter, the other parameter, nothing works, thanks for your help, good-bye...) RS-485 is working fine. The speed command on the keypad is changeable from the PLC when in "AUTO" on the keypad (while not changeable from the keypad) but won't start. However, when in "OFF" on the keypad, the PLC cannot change the speed command (while the keypad can), but can start the VFD!

In other words, when the PLC can change the speed command (in AUTO) it cannot start the VFD, and the keypad cannot start the VFD nor change the speed command. But when the PLC can start the VFD (in OFF) it cannot change the speed command, but the keypad can change the speed command (but not start the VFD.)

Not asking for advice at this point, just sharing a bizarre situation. I'm working on a spreadsheet app where I can enter the hexadecimal values of the Command Words and Status Words from the RS-485/Modbus comms as displayed on the keypad and see which bits are ON or OFF and what they control or indicate.

 

[petersonra]

My guess is there are parameters you can set that tell the VFD where to receive the various commands from and those are not set correct. I don't have any experience with modbus on these drives but that kind of thing is common on other brands.

It's maddening sometimes because they made it so convoluted, but I guess it sort of makes sense so someone could start/stop the VFD via the keypad and set the speed over modbus.

There is a manual dedicated just to control via the serial port that you might want to upload.

I am pretty sure the keypad has to show auto for the modbus commands to work though

 

[TwoBlocked]

Thanks, I got the manuals. ABB is bad for "Oh, you also got to ..." Fortunately, the programming gal and I work well together, focusing on what's right, not caring who is right. I expect the solution will be one of those "Whooda Thunk It ???"

 

[garbo]

Place that I retired from had over 500 VFD'S. 75% Danfoss & the remainder ABB. When our talented JCI tech had problems with Modbuss I called our Danfoss tech that gave him a run for his money for awhile. He had to go back to his truck and retrieve a Danfoss program book over 1" thick. After a short time he had it running. Dealt with A & B drive tech support and them & Danfoss were best in class. Would not even give Prima Donna's ABB techs a D. Took me two weeks & at least three e mails for them to finally tell me how to access the DC Buss voltage. Contractor threw all the manuels away. Every phone call they would ask " Why do you want to know that ". We had large VFD 125 & 15O HP cabinets with drive bypass. ABB tech support gave me a hard time when I asked if theses double door cabinets have a thermostat for expensive 12" 240 volt fans that ran continuous. We had several for chiller pumps in climate controlled mechanical rooms where motors did not run in the winter but they liked to test them for a few minutes every week or two. Nope fans did not have a thermostat. Danfoss fans in same rooms with drives running cycled on & off.

 

[TwoBlocked]

Place that I retired from had over 500 VFD'S. 75% Danfoss & the remainder ABB. When our talented JCI tech had problems with Modbuss I called our Danfoss tech that gave him a run for his money for awhile. He had to go back to his truck and retrieve a Danfoss program book over 1" thick. After a short time he had it running. Dealt with A & B drive tech support and them & Danfoss were best in class. Would not even give Prima Donna's ABB techs a D. Took me two weeks & at least three e mails for them to finally tell me how to access the DC Buss voltage. Contractor threw all the manuels away. Every phone call they would ask " Why do you want to know that ". We had large VFD 125 & 15O HP cabinets with drive bypass. ABB tech support gave me a hard time when I asked if theses double door cabinets have a thermostat for expensive 12" 240 volt fans that ran continuous. We had several for chiller pumps in climate controlled mechanical rooms where motors did not run in the winter but they liked to test them for a few minutes every week or two. Nope fans did not have a thermostat. Danfoss fans in same rooms with drives running cycled on & off.

Yeah, the ACS800 has fans that run constantly, and when they run long enough, a warning comes up saying to replace the fan. OK, but the only way to reset the fan hours is to hook up to the VFD with a $1,000 fiber communicator and program.

 

[TwoBlocked]

Got it running. It was very painful, took all day, and not sure just what all caused the problems. (Lots of fingers in the pot...) Had 2 ABB techs help out via phone, and a senior programmer via remoting to the laptop. Tried a couple different macros, found out that there were different sets of hexadecimal codes according to the protocol, but wasn't obvious what was what from the literature nor from the keypad. Thought we had it until cycled the power to the drive, and then it wouldn't start. By accident, found out one of the permissives needed to be toggled in order to release an inhibit. Then the programmer gal tried to get an AB Powerflex 400 going. Called tech support, but they wouldn't help because none of the companies involved had an account or service agreement or something.

 

[petersonra]

Got it running. It was very painful, took all day, and not sure just what all caused the problems. (Lots of fingers in the pot...) Had 2 ABB techs help out via phone, and a senior programmer via remoting to the laptop. Tried a couple different macros, found out that there were different sets of hexadecimal codes according to the protocol, but wasn't obvious what was what from the literature nor from the keypad. Thought we had it until cycled the power to the drive, and then it wouldn't start. By accident, found out one of the permissives needed to be toggled in order to release an inhibit. Then the programmer gal tried to get an AB Powerflex 400 going. Called tech support, but they wouldn't help because none of the companies involved had an account or service agreement or something.

you get paid by the hour so you came out OK. That is all that matters.

 

[TwoBlocked]

you get paid by the hour so you came out OK. That is all that matters.

Yeah, I learned a thing or two also.

 

[garbo]

you get paid by the hour so you came out OK. That is all that matters.

Years ago we had a lot of Reliance DC drives on a large machine. Every time we called tech support for guidance they would give us the runaround and always wanted to send out a tech. Several times when they came out had the problem fixed in less then a hour but charged four hours labor and travel time ( were located at the other end if our city ).