AB PLC5/5 to control VFD Drive

Hello Experts!!
I am working on a project for a client where the PLC is old AB PLC5/5. The proposal is to use this PLC for ABB ACS800 VFD Drive control over remote I.O
I would like to know what challenges were faced in trying to accomplish speed control by AB PLC 5/5.
Due to the client standards we are going hardwired from Drive to Remote I.O.
Any answers are appreciated.

Depends on what remote I.O. That you use. There are many choices so you will need to be much more specific if we are to be of any help.

PLC kid I am concerned
1. Sending speed ref to the drive
2. And on the controlling aspect of the PLC as well.
The PLC has to modulate the speed based off a pressure signal.
Can this PLC5/5 handle VFD control?

I have no information on how the remote I.Os are connected since the client wouldn't let us open their panel.
thanks

What is the exact number on the plc? What communication protocol are you planning on using? DeviceNet is probably the only option you have for the ACS800. PLC 5 don't have Ethernet I/O control that you need for the EthernetIP adapter for those drives.
For a simple system like that you may be better off just using analog outputs for the speed reference. Discrete controls are hard to beat when troubleshooting by someone who might not have a laptop to use.

Thanks Jeff,
Client has not confirmed the exact PLC no however If we do go for hardwire control, can the PLC be able to calculate and control the speed of the VFD?
What I mean is will it be an effective control in terms of scan time of the PLC.?

It is all relative to the process. I have seen systems where a PLC5 couldn't handle it. Is this a Highspeed bottling line or a slow temperature control application.

Without knowing the full system I would say yes the PLC 5 could handle a PID for VFD speed loop calculation.

Jeff,
This is going to be speed control of VFD for a pump in water injection facility.

Water injection can be very crude or very exact. The plc 5 might be ok we will need to know a lot more details

Just a couple of comments. Your control loop can take place in the drive instead of the PLC. If this is a new application, I would use the ACS850.

I am not sure what comm adaptors ABB makes for that series drive. I have recently controlled a new A-B PowerFlex750 series drive via RIO on a PLC 5/40. While A-B doesn't make a 750 series RIO card, an older 20-comm-r can be used with a 20-750-20COMM adaptor.

PLC 5 processors have also been used with process control drives utilizing digital and analog controls. That said, let me echo what others have mentioned: PLC part number, processor scan time, among other things are critical pieces of information that you'll need to share to get a helpful response.

If you are required to use remote I/O, you will need to make sure that appropriate rack space is available for the channel you're using. The drive adaptor may force you to a minimum 1/2 or full rack, for example.