adccommunitymod (AutomationDirect) asked a question.
Created Date: January 25,2017
Created By: jtak101
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To continue my week of questions, ran into another problem. I have a F2-08AD-1 analog input, DoMore CPU, have a pressure transducer going to the input, I have always used voltage output transducers, but this time decided to be different and get 4-20mA output, now realizing I shouldn't of.. I am reading 0 pressure in the PLC even when I put pressure on the system. Attached is the loop current chart from the transducer manufacturer. I read the manual for the analog card and it says it has 250ohm resistance, I am getting 24V to the analog card, and 24V to the transducer (don't have much voltage drop, short runs) I would need to add a 500ohm resistor to get this to work? Am I understanding this correctly? If so, do I wire the resistor in series to each of the channels on the input card and connect the output wire of the transducer to the resistor and the resistor to the card channels? Thanks,
Created Date: January 25,2017
Created by: jtak101
To continue my week of questions, ran into another problem. I have a F2-08AD-1 analog input, DoMore CPU, have a pressure transducer going to the input, I have always used voltage output transducers, but this time decided to be different and get 4-20mA output, now realizing I shouldn't of.. I am reading 0 pressure in the PLC even when I put pressure on the system. Attached is the loop current chart from the transducer manufacturer. I read the manual for the analog card and it says it has 250ohm resistance, I am getting 24V to the analog card, and 24V to the transducer (don't have much voltage drop, short runs) I would need to add a 500ohm resistor to get this to work? Am I understanding this correctly? If so, do I wire the resistor in series to each of the channels on the input card and connect the output wire of the transducer to the resistor and the resistor to the card channels? Thanks,
Created Date: January 25,2017
Created by: Mike Nash
24V supply and 250 ohm looks fine per the graph. That is a MINIMUM supply voltage of 14.5VDC to required to function, not the max allowed.
If you measure voltage across the analog card input you should have 1 to 5 VDC for 4 to 20 mA of transducer signal. If you have that, the transducer is good but you may have a setup issue in the PLC or a wiring issue.
Created Date: January 25,2017
Created by: jtak101
The measurement across do you mean from CH+ to the 0V on the card?
Wiring I am pretty sure on, its 4 wire, 1 to 24VDC, 1 to ground, the other 2 can be interchanged 1 is for the 0VDC the other is signal
Setup issue in the PLC?? could you elaborate, I didn't do any set up. When I hooked the cable up to the PLC Domore recognized the card and location, then from what I read on the numbering it starts at WX0, WX1, etc. (if its the first analog in card) which it is. Is there something else I should of done? Thanks,
Created Date: January 25,2017
Created by: plcnut
Please post a diagram of how you have it wired.
Created Date: January 25,2017
Created by: Mike Nash
The measurement across do you mean from CH+ to the 0V on the card?
Yes
Wiring I am pretty sure on, its 4 wire, 1 to 24VDC, 1 to ground, the other 2 can be interchanged 1 is for the 0VDC the other is signal
Interchanged? Make sure the polarity is CH+ is positive when checking voltage with meter.
Setup issue in the PLC?? could you elaborate, I didn't do any set up. When I hooked the cable up to the PLC Domore recognized the card and location, then from what I read on the numbering it starts at WX0, WX1, etc. (if its the first analog in card) which it is. Is there something else I should of done? Thanks,
In Do-more Designer (DmD) In System Configuration>I/O Configuration>I/O Mappings you can see for sure where DmD assigned the card addresses. There are also X bits that will allow you to see each channel's status:
On when the transmitter is broken, the external 24VDC input power is missing or terminal block is removed.
Otherwise, you are right in that the module has no setup in DmD and you should see 0-4095 if the signal is in range at WX0 for Channel 1+ (as long as that is the address assigned in I/O Mappings.)
Check the 3 jumpers on the module for channel selection also per the manual.
Created Date: January 25,2017
Created by: alexb
Yes measure the voltage across the channel + and 0V (when connected to the analog module). I'm uncertain about the part where "the other 2 can be interchanged ", can you provide a link to the sensor datasheet? The picture you linked is more of an indication of how long the wiring can be based on the voltage (depending on the sense resistor used which in the F2-08AD-1 is 250ohm). Basically, don't add a resistor.
Created Date: January 25,2017
Created by: jtak101
Please post a diagram of how you have it wired.
Attached is the wiring diagram for the transducer, I have pin 1 connected to 24VDC, pin 2 to 0 VDC, pin 3 is what I ran to CH +1 on the PLC Analog in card, pin 4 Ground.
Created Date: January 25,2017
Created by: alexb
Ok that makes more sense. This is a 4-20mA loop powered device (or 4-20mA two wire transmitter), so here is how you will connect it to the PLC:
1) +24V to the V+
2) Either V- to the ch+ of the analog module. Read the note in your last picture: *Use either V- termination on G2 with 4-20mA output.
3) make sure the 24V and 0V of the analog module is connected to the power supply.
If you are still not sure, take a look at the spec sheet for the F2-08AD-1, on the first page they show a diagram for various sensor configurations, including the 2-wire 4-20mA transmitters.
Alex
Created Date: January 25,2017
Created by: Mike Nash
Just for future reference, if you really, really want quick help, supply ALL of the pertinent info rather than dribbling it out like it was a guessing game. You still haven't supplied the transducer part number, never mind a link.
I'm not trying to hammer you, just trying to help you help yourself out.
Created Date: January 25,2017
Created by: jtak101
Ok that makes more sense. This is a 4-20mA loop powered device (or 4-20mA two wire transmitter), so here is how you will connect it to the PLC:
1) +24V to the V+
2) Either V- to the ch+ of the analog module. Read the note in your last picture: *Use either V- termination on G2 with 4-20mA output.
3) make sure the 24V and 0V of the analog module is connected to the power supply.
If you are still not sure, take a look at the spec sheet for the F2-08AD-1, on the first page they show a diagram for various sensor configurations, including the 2-wire 4-20mA transmitters.
Alex
Hey Alex, ok so my error was that I hooked both V- up connections up and I shouldn't of, correct? I hooked 1 up to the ch+ of the analog module and the other V- to 0VDC, but I just need to pull the one that I have connected to the 0VDC?
I do have 24V and 0V connected to the module itself.
Thanks,