Dears,

Today during our loop check in new chemical complex, we came a cross DP flow xmitter installed to Tricon shutdown system. This xmitter calibrated linear as per our standards and the square root is implemented in the system. We noticed that it was even in the system linear, so we added a square root function block in the logic but we couldn't succeed.

Now is there any one of came a cross the same situation, and which block is used, is customized block or standard one.

BR

 

Hello Kareem,

I hope you are using OPC. Because you can do that easily with it. If you do, all you need to do is:

1-Map an Alias to that OPC item (xmitter value holder)

2-Choose the scaling tab and expression and put in your formula.

3-Click apply and then in your HMI or your monitoring application point to that item. You are done.

If you are not using OPC, you can get it from here:
http://www.matrikonopc.com/opc-drivers/249/base-driver-details.aspx

If you need some tutorials about what OPC is, visit here:
http://www.matrikonopc.com/resources/opc-tutorials.aspx

Hope that was helpful, let me know how it went

Thanks,
Wassim Daoud
Global Solutions Architect
www.MatrikonOPC.com

 

I tested the following in both Tristation 3.1 and 4.1. You did not state what version you have.

Your analog input will need to go first through a scaling function block AIN. The AIN output can then go through a square root function block SQRT, followed by a multiplier function block MUL.

This assumes a 4-20ma analog input to the Tricon, and a differential pressure transmitter across an orifice.

You may also consider adding additional logic that detects analog input bad quality, by comparing the raw input to low and high compare blocks. Based on bad quality you may want to alarm and/or take other action.

There is no need to export the value to another system outside of your safety system for this simple math.

John

 

Dears thanks for your reply,

Now a new concern is which is better to implement the square root function in the SYSTEM ((( DCS or ESD ))) or in the field Transmitter.

I know that technically both are same, but the question which is better in terms of accuracy and any another technical reason.

Please share you experience.

BR

 

Kareem,

well i think you should have in the ESD, because it's safer to have it there. plus your DCS not supposed to take control of any ESD signals unless it's initializing the trip.

Regarding, square root. You should implement it in ESD after the AI block. There is one block called SQRT in tricon can do it for you.

My best regards