Calibrating SLC 5/03

tkessler8

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Join Date
Mar 2017
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Indiana
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I have a vacuum furnace running an Allen Bradley SLC 5/03 with a PV 550, I am new to PLC's and using RSLogix 500. My issue is that the control t/c is putting in 900 for instance but then the PLC is spitting out 863. How can I correct this?
 
welcome to the forum ...

it's going to be hard to give you detailed answers - unless you can give us detailed information ...

question: are you allowed to post the ENTIRE project file? ... (RSS extension) ... note that you'll have to zip it first (forum rule) ...

if you can post it - just put it into this thread as an attachment to another post ...

note: some forum members will not download files from a "dropbox" or "cloud" address for security reasons ...
 
In the file you posted none of the thermocouple channels on your TC input card are enabled.

Is the input in question connected to that card?

Or post a more updated program.

Tell us more about how the temperature input is getting into the PLC. Type of thermocouple, Transmitter? scaling of the transmitter if you have one.
Which card it is connected to (channel)
 
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It would be the process variable I:8/00 in module 1746-NT4. I am not sure how they could not be activated that is the program the furnace is currently running and everything works fine other than the bad readings on the controller. I know my t/c reads the correct temperature because I have checked it with a handheld and I drove the input with a handheld also that was how I determined it has to be something to do with the PLC.

I am a super beginner on this stuff so I may be misunderstanding what you are saying, but that program was uploaded into the PLC just a couple days ago.
 
The program you posted the channels on the thermocouple card are not enable. Take a look for yourself, under I/O configuration.

Can you check that and post the working program. Or go online and check it.
 
It would be the process variable I:8/00 in module 1746-NT4. I am not sure how they could not be activated that is the program the furnace is currently running and everything works fine other than the bad readings on the controller. I know my t/c reads the correct temperature because I have checked it with a handheld and I drove the input with a handheld also that was how I determined it has to be something to do with the PLC.

I am a super beginner on this stuff so I may be misunderstanding what you are saying, but that program was uploaded into the PLC just a couple days ago.


Mickey is correct; in the file you've posted none of the channels of the 1747-NT4 (Analog 4 Channel Thermocouple Input Module) in Slot 8 are enabled.
Anyway, I:8 value (=224) is being offset (+) with N7:72 (with a value of 10 in your application copy) then the result is SCP-ed (Scaled with Parameters) into N27:78 which represents the Process variable of a PID instruction.
Your copy of the application states that said N27:78 Process variable is at Setpoint, so the PID is doing its job.
The unknown is the N7:72 offset; it has only one occurrence and it's probably being written to by the HMI. This probably is a calibration tool.

You will need to find the N7:72 within the HMI application (some Numeric Input Entry object related address) and try adjusting it from the PanelView HMI in order to solve the issue.
 
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Mickey how did you get that to pop up like that, like I said I am super new at this trying to learn how to do it, it should probably be known that I did not write this program myself either.
 
There is another problem, in Lad 2 rung 2 there is a FLL instruction that is writing configuration data to the cards output words. You should delete this instruction.

When you configure the card thru the I/O configuration window the software will create a "Copy" instruction for you to copy the cards configuration setup.

Reread dmargineau post and double check the "SCP" instruction parameters as it looks like you are using values for degrees Celsius not Fahrenheit.
 
Yes we are using celsius on this furnace we bought it used and that is how it came in all our other equipment runs Honeywell so we aren't really too sure how to do a lot with the RSLogix, if you could tell me how to get it to read Fahrenheit also that would be awesome. Thanks again guys I have been fighting this furnace for awhile to get it into production.
 
Okay so new issue I tried to connect to PLC and I am getting a communication error. I attached a picture of what I am seeing.

Com Error.jpg
 

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