Signal [mA] missing somewhere

[BryanG]

This gives more information on the Analog output.

http://us.mt.com/us/en/home/product...ndicators/Process_Terminals/IND331_harsh.html

Download the PLC interface manual. Nowhere does it say if the output is active or passive. As has been suggested try connecting the output straight to the PLC and see it if works without the power supply. You might think that because it is isolated it must be passive but it ain't necessarily so.

 

[danw]

Here's the diagram for the analog output:

Usually loop powered, passive outputs will show an external power supply. I continue to suspect that this an active output that does not need or want a 24Vdc supply, in fact, 24V might have damaged it.

 

[JesperMP]

Where poor manual with regards to the curent output.
But after reading what little there is to read, I guess that the output is powered internally (though with galvanic isolation).
Connect the + terminal to the analog input on the PLC.
Connect the - terminal to the common ground on the PLC, or the analog minus on the PLC (if there is one).
But first, just measure with a meter between the + and - terminals.

 

[JesperMP]

[...] 24V might have damaged it.

Yep.
Also, if fumbling around with 24V, it can have damaged the analog input in the PLC.

 

[Roy Matson]

I agree with the rest, disconnect the wires at the weigh scale and see if it puts out mA, if it does you dont need to have the 24V supply in the loop, just wire from output to input

 

[Daye.04]

Then that is definetely what I will do. The strange this, though, is that we have several of these displays. All connected in the same way. And all working perfectly fine except for these two ...

 

[KalleOlsen]

Then that is definetely what I will do. The strange this, though, is that we have several of these displays. All connected in the same way. And all working perfectly fine except for these two ...

Could it be that you can change a channel between 2 and 4 wire in the hardware konfiguration program?

 

[Daye.04]

It could very well be. But then I must have misunderstood something. As seen here, it doesn't show any option to change the behaviour of the analoge option