I just added a CV and a Pressure transmitter to an existing program. I added a new PID so that the PT would control the valve. for some reason after landing the points and downloading the updated program the pressure transmitter will not show PV in the PID. it reads in the field and shows a 4 to 20mA loop but shows no value on the PID. Anyone got an idea of what I did wrong?
Live program
- Thread starter wsmith308
- Start date
Could it simply be the 4-20mA is wired backwards to the PLC?
If the measured current is under 4mA, or negative, the PLC will display the 4mA value.
Conversely, as I found out before, if the reported signal is always the 20mA value then the input is probably set to volts, not mA.
If the measured current is under 4mA, or negative, the PLC will display the 4mA value.
Conversely, as I found out before, if the reported signal is always the 20mA value then the input is probably set to volts, not mA.
Ken Moore
Lifetime Supporting Member
So we don't know what brand or model of PLC. So a few guesses.
The channel that the PT is connected to is not enabled.
It is enabled, but it is not configured for mA input.
Have you confirmed you have a signal at the input module?
The channel that the PT is connected to is not enabled.
It is enabled, but it is not configured for mA input.
Have you confirmed you have a signal at the input module?
Check the scaling tab of your PID setup window. That one has bitten me a few times - even if all the values are correct, and you don't need to change any, you still have to go in there and do something so that the PID will initialise and start calculating values
Go to the rung with the PID, add a rung in online edit. On that rung put an OTE "Yep_Its_Getting_Scanned" bit, accept and test. - if the routine with the PID is not being scanned this bit won't come on.
If it does come on then edit the line to MOV the input value to a new DINT, and see if that DINT reflects the current change.
If it does come on then edit the line to MOV the input value to a new DINT, and see if that DINT reflects the current change.
Similar Topics
Good Day All,
I currently have a request to update an AOI and a shutdown of the place it's to be updated has to be shutdown which is not...
So I work at a site that is 99% Honeywell, but we have a few stand alone PLC devices so excuse my ignorance on the subject.
I need to live view a...
Hi all,
This is going to be a long post apologies. I'm also a complete beginner to the world of PLCs.
I'm currently working on my first ever...
Hello! New to the forum and new to PLCs in general. We have an ABB AC500 PLC (circa 2012?) and we are using CoDeSys (version 2.something). We're...
Story time:
We have two similar machines on a Factorytalk View Distributed Network. This SE server has several different machines on it as well...