GE PME 8.6 PID_IND internal SP not getting SP

bill2bhappy

Member
Join Date
Nov 2015
Location
Danbury, CT
Posts
5
I have a head scratcher I have a PID in auto that is getting the external SP. The internal SP is zero I have looked for something writing to the internal SP and there are no other references in the software. This is in PME 8.6 with the SIM 16 installed online with a CPE-310. The PID is enabled, in auto, not in override, the high clamp is 32000 counts the low clamp is 0 counts, SP range is 0-1400 (SCFM) for a flow controller and the external SP into the PID is 80 (SCFM) :unsure: does anyone have any other ideas of what to try? I have a case in with GE but been waiting to hear back with a high priority for a while thought someone else might have some ideas.
 
While online can you Right click on the set point register and write value. Put a one or something and see if it writes the one into the register. Ff it writes the one or whatever number you throw at it there is nothing else writing to it. Are you writing an Integer or a Real Floating point. Make sure if you are using a subroutine you have the called blocks and if you are writing from an external device you are writing the correct source Integer, word, floating point, ect.Some HMI are explicit how it reads and writes.. You have established proper comms from the writing device? Check that you don't have an overlapping register.
 
Thanks for more things to check, There are no external references listed when I search the xxx.[15] (internal SP) in the array but when I put an always off in front of the PID I can change the internal SP by editing [15] but when I remove the always off the internal SP goes to zero. The block is being called and all the reads and writes are working as I can put the PID in manual and run the valve 0-100 and in Auto I can change the input SP to the PID. I cannot find or think of a way to get force the internal SP to zero with out an external write and still waiting for GE to get back :-D
 
%Ref+0015
Internal SP
N/A. Set and maintained by the Controller. Non-configurable.
Tracks SP in. Must be set externally if Override bit = 1. Page 349 GFK-2950_PACSystems_R_Prog_Ref_Manual.pdf

If the Override bit (bit 0) is set to 1, the Control Word and the internal SP, PV and CV parameters must be used for remote operation of the PID block (see below). This allows a remote operator interface device, such as a computer, to take control away from the application program.

Page 349 of GFK-2950
 
Last edited:
Is the PID loop behaving as if the SP is zero, presumably driving the CV to zero? If you change the lower clamp value does the CV become equal to the new lower clamp. You said you check for dual use of word 15 of the PID array. Are there any DINT or REAL variables assigned to the same address as word 14 of the PID array which would overlap with word 15?
 
Override is not set = 0 but the internal SP is not tracking the input SP. The SP is 80 while the [15] is 0. Still waiting on GE to get back glad we pay this much for the priority technical support lol.
 
So we got it. The issue was a integer variable at %9679 was changed to a Real last Friday. So it occupied 9679 and 9680. %R9680 is the SP for the flow controller that was creating a zero value that was being tracked into the PID. The SP that was an integer was still displaying the value of 4 in the end it was a stepped on address but was confusing as the external SP indicated 4 while the integer value that was in the stack was a zero.
 
Always a good feeling to find the root of an issue.. Glad you got it quickly.. A good tool in Proficy is look at the Reference View Tables. You can see a bit more what is going on. I remember not to long ago getting a motion controller set up correctly and was going from word to Int To real through External write and it wrote to the second register and when i went from real to word or Int cant remember which the value was stuck in the second register and wouldn't write to the register. so i had to manually write a 0 to the second R and all worked as it should.. couldn't see it but it was clear as day in the Reference View Table..
 
For better PID response, I usually convert the SP and the PV from REAL to INT and feed them into the PID block.
ie....SP is 80.5 (REAL) and the converted to INT (SPx10 then REAL to INT). Now you are feeding 805 to the SP of the PID block.
Then PV is converted from REAL to INT the same way.

Now the PID is actually responding to 0.1 change.
 
For better PID response, I usually convert the SP and the PV from REAL to INT and feed them into the PID block.
ie....SP is 80.5 (REAL) and the converted to INT (SPx10 then REAL to INT). Now you are feeding 805 to the SP of the PID block.
Then PV is converted from REAL to INT the same way.

Now the PID is actually responding to 0.1 change.

This way your PID can be a little "looser'. If you have a swing from 801 to 809, you are really only in 80.1 to 80.9 range.
 

Similar Topics

Hi, I've got a PID block in my RX3i program wherein the setpoint is 390, my feedback is 200, and the CV is the difference, 190. When I change PV...
Replies
1
Views
1,237
Hi I am wondering if the RXI-042 PLC model (below PN) is programable via Proficy Machine Endition, if so, what is the firmware version needed for...
Replies
2
Views
68
Hello guys i have a HBM PME MP55 and i want to connect with a pc, what type of cable does it need because on its manual it say on a terminal 2...
Replies
0
Views
308
I don't have much experience in programming. I can do simple configuration. it is like this. i want to add something to the existing ladder...
Replies
39
Views
6,032
hey i am new to PME proficy-machine-edition-9-70-emerson, can anyone please help me in knowing how to install a crack version. usually i used to...
Replies
4
Views
1,249
Back
Top Bottom