abb acs350 pid problem

[gary.houston]

Hi All !
I am having a problem with a pressure/vfd controlled water irrigation system.
The basic set-up is a danfoss 2 wire pressure tx 4-20mA
linked directly to an abb acs350 vfd onto AI2.
AI1 has a fixed reference 7.6mA
2x digital inputs are connected to DI2 and DI5 (pid)
The problem is that when the external controller which controls the vfd start/stop function ALL of the vfd digital inputs have 24v present.
When the input to DI2 and DI5 is OFF (0v) ALL the DI's return to 0v.
Obviously, if all the DI's are receiving an input then the drive logic will hang.
I suspect a faulty vfd, but all the DI's should be internally protected from short circuit etc.
Is there a PNP/NPN switching function I have missed ?
Any help appreciated
Many regerds
Gary

 

[milldrone]

2x digital inputs are connected to DI2 and DI5 (pid)
The problem is that when the external controller which controls the vfd start/stop function ALL of the vfd digital inputs have 24v present.
When the input to DI2 and DI5 is OFF (0v) ALL the DI's return to 0v.
Obviously, if all the DI's are receiving an input then the drive logic will hang.

Just a shot in the dark. Do you have the jumper installed between #10 and #11

 

[DickDV]

milldrone has it on the nose. The Digital Inputs are floating and need the bottom side reference connected with a jumper from terminals 10 to 11.

 

[gary.houston]

Thanks Gents,
You are spot-on.

The drive was wired for a two-wire pressure tx where
T9 supplies 24v
T5 is AI2 return
and a common link on T6 and T10
I missed the DCOM connection

Fantastic !

Many thanks

 

[gary.houston]

Evening all !
Thanks to the Gents for your advice.
I set the drive as advised and it runs perfectly.
Cracking wee website !
Regards