which is best digital calculation point or logic diagram or script

[abdul-rahman]

I have a Logic Diagram  to get some of bit from 16pit unsigned point and I want to Use a digital calculation point , so I want to know which is best digital calculation point or logic diagram or script (Execution Performance , Execution ,  Execution Performance , Reliability )

[sbeadle]

Opinions will vary, and the circumstances you have may be different.

But - if you can use a Calculation Point, use it. Then use Logic if it is more complex.

Client script is client-side, so might not be suitable at all.

[du5tin]

Order of preference: calculation point, the logic program (FBD/ST/LAD). I would use these two options if you need to do anything else with the resulting true/false bit server-side like alarm redirections or history. If this is just for display on graphics you might be able to get away with script but functionality will be very limited (display only, no history,  and the script only runs when the screen is open by a user). 

The better (best!) place to do this sort of bit "unpacking" is in the PLC or RTU but I understand that is not always possible. 

If this is only a handful of points with a limited number of discrete bits to check I think using a logic program would work pretty well. Just make sure the logic program is set to run on input processed (if the scan time is 15 seconds or more) or on interval once a minute. We have done this for certain pump off controllers in O&G industry where they used packed bits in UINT registers to store the state of the machine or consolidating the machine's alarms. 

[abdul-rahman]

i want to display the state of RTU on a Control Faceplate rapidly , and the number of RTU exceed 300 RTU , each of them have a unique Control faceplate , so which of 3 way (digital calculation point or logic diagram or script) is most fast to show the state of RTU .

Note : the RTU Send a byte of data each bit indicate a state of RTU like ( RTU closed , RTU Trip etc...) 

[sbeadle]

Seems like a calc point would be best.

[AndrewScott · Accepted solution]

You've not said which protocol / driver you're using but if its the Advanced Modbus driver then you can use the Bit Offset and Number of Bits properties of Advanced Modbus Generic Digital Input Points to directly read a particular bit from a Modbus register. That way you don't need any calculation points or logic at all.

The help has more details, see Driver Reference > Modbus - Advanced Driver > Configuring Digital Points > Common Point Properties 

Some other drivers, such as Advanced OPC, also have these same features.

Driver Reference > OPC - Advanced Driver > Configuring Advanced OPC Digital Points