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LOGIC CHARTS IN YOKOGAWA CENTUM CS DCS

  • Thread starter Mihir Ramkrishna
  • Start date
M

Thread Starter

Mihir Ramkrishna

In LC-16 & LC-64 logic chart blocks sometimes due to process upsets it is required to put them in manual mode.Since the logic charts are in manual, the dynamic updating of the inputs does not take place. Due to this if the logic chart is put back to AUTO mode and if any input condition "not satisfied" exists, then the output changes to "not satisfied" state. So all the good work of saving the equipment from trip goes down the drain. I would like to assign modifier to all the inputs in logic charts which will change state with their condition change. At present all the input face plates in the logic charts have to be opened and checked for any "not satisfied" condition which is tedious and time consuming.

I know the facility of modifier does not exist like that in graphis. Has any one encountered such problem and subsequent solution for it???
 
B

Benny J. Lopez

Well, you do a logic chart because I believe you want to have a sort of validation of condition based on your inputs, so if ever you change mode from AUTO to MANUAL and from MANUAL to AUTO it doesn't matter because your inputs tells the logic what the real situation in the field or from subsequent conditions. If your issues is related to how to find those inputs which is not in 'satisfied' state, I recommend you to install the 'logic display package' so, right there in ICS you'll have a real time view of the logic itself. If you don't want to intall that package, I also recommend to use a graphical representation of that particular logic which can be seen by operator in the ICS. The bottom line is, we create logics because we want to satisfy those permissive(inputs)in order to have a desired output and the only thing that an engineer/operator can do is to monitor effectively those logics and find out why certain conditions/input is not satisfied.
 
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Mihir Ramkrishna

Hi Benny
We do have logic chart display package installed in the system. The problem we face is, when the logic is in manual mode, the display in the display package does update.... I think this is a system limitation...

Regards
 
V

Veeresh Prasad Tiruvuri

In "MAN" block mode, Sequence Tables (Cause & Effect Matrix) of Yokogawa have process dynamic value updation.
So if you are keen in pre-checking your permissives/pre-trip conditions, and if you can not afford to have addl Graphic window displays for these logics (customised generation), you have to move from Logic Charts to Sequence Tables.
Sequece Tables will give Dynamic Parameter Updation in MAN mode, and will not process the outputs.
Where as Logic charts in Man mode can not update dynamics, but automatic output will be executed if permissions are satisfied the moment u put in AUT mode.

regards,
Veeresh Prasad Tiruvuri
 
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