Remote SP on a Temp Controller...Need Advice

JoseM

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J
Join Date
Jul 2011
Location
Texas
Posts
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Have any of you guys done any "Remote Set Point" application on a temperature controller.

I have this controller that accepts a 4-20ma signal which is suppose to tell it what "Set Point" temperature to tun. I want to integrate this functionality into an SLC 5/04.

I added an SCP instruction into the code but it doesn't seem to be working. I don't see any variation on the current with a voltmeter attached to the connections coming from the analog card.
 
What model of analog output card are you using ?

Describe your configuration and wiring of the module. Does it run other analog output channels successfully ?

In general you're going to put a multimeter in series with the module, in current mode. That will allow it to directly measure the current flowing through it.

Some analog output modules don't provide source current from the backplane of the controller, or they make it selectable. You're going to have to get out the installation documents for your precise module to know how to provide the loop power.
 
Ken,

I got the analog card to output the correct 4-20 ma signal after I had to change some settings on the SCP instructions.

I'm working with an Omron E5EN-H temperature controller and it says that the capabilities for "Remote Set Point" are built on the unit. When I send the signal to the controller the set point doesn't change to reflect the new value.
 
I configured the controller using the page mention. The "Remote SP" feature is enable. I try with the Remote SP upper limit and lower limit set to the default values and to other values but it didn't seem to make a difference.

I don't know if my problem is scaling within the "Temperature Controller" or if I'm missing another parameter that I have to change.
 
As well as "Remote SP Enable" it looks like there is another parameter "SP Mode" which can be changed between "LSP" for local setpoint and "RSP" for remote setpoint.
 
I set that one as well Brendan while testing the operation of the SCP instruction. I'm getting the 4 - 20 ma to the Temp Controller but the analog signal is not being interpret by the controller.
 
Not sure what else it could be... :unsure:

Just to confirm...
  • The "RSP" indicator is definitely illuminated on the front display?
  • The 4-20ma loop is wired correctly?
šŸ»

-Eric
 
When I switch the "SP Mode" to Remote SP the "RSP" indicator illuminates and it blinks.

The analog signal is wired correctly and the SCP instruction is set up correctly because I can put a multimeter in series with the analog card and I can measure the change in amps when I change the "Set Point" on the PLC.

I set the Input Min and Input Max between 0 - 130 F, so when I put 0 F the current is 4 ma and when I set 130 F the current is 20 ma.

I guess my question is, How does the temp controller knows that 0 : 4 ma and that 130 : 20 ma?

I did a test thinking that my issue was scaling and I took the Remote SP Upper Limit and changed it to 130 F and the Remote SP Lower Limit to 0 but this change didn't yield any positive outcome.
 
Last edited:
What terminals have you got connected for the 4-20mA signal?

The manual states that terminals 29 and 30 should be used for Remote SP Input.

Terminal 29 is +, 30 is -.

JoseM said:
I guess my question is, How does the temp controller knows that 0 : 4 ma and that 130 : 20 ma?
Click to expand...

This looks like it is determined by the parameters Remote SP Upper/Lower Limit
 
JoseM said:
When I switch the "SP Mode" to Remote SP the "RSP" indicator illuminates and it blinks.
Click to expand...

From the manual:

"The remote SP input can be input in a range of āˆ’10% to 110% of 4 to 20
mA. Input values outside of this range treated as out-of-range input val-
ues (RSP input error) and clamped to the upper or lower limit. In SP
mode, the RSP single indicator will flash, and in local SP mode the No. 2
indicator for the Remote SP Monitor will flash."

The controller is seeing a value outside the 4-20ma range. Not sure why. Maybe you have the polarity backwards at the controller?... :confused:

šŸ»

-Eric
 
You were right Eric. I messed up by switching the polarity between the Temp Controller and the Analog module. Now is working perfectly.Thank you all for your help.
 

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