Writing a constant value to a register

Hello everyone,
I am new to this forum and would like to ask a question.i presently have a Control logix plc with rsview scada.Now, i have written a logic for lighting control with reference as plc time and its functioning perfect.I want to customize set time through scada by writing a value and energize my lighting output as per my requirements.I have used LES and GRT blocks in logic for control with a constant value.How to assign customize this constant value by keying it in SCADA?

You make the 'Constant' a tag in the PLC, and write to it.

I would say that the value is not constant, if you are planning on the user being able to change it. As such it will be just another tag in the program.

I have attached the logic for energising lighting output with fucntional blocks.in A>B where B is a constant for which entry is done in logic only.Now without accessing logic is it possible to key in B value through SCADA?
P.S. I am new to RS logix and worked in Melsoft previously

Ghouse said:

I have attached the logic for energising lighting output with fucntional blocks.in A>B where B is a constant for which entry is done in logic only.Now without accessing logic is it possible to key in B value through SCADA?
P.S. I am new to RS logix and worked in Melsoft previously

Click to expand...

No, not possible.


Source B is entered as a "literal" into the PLC code, not a "constant", and will not be changeable by anything.


The only way is to get access to the code for editing the rung, and change Source B in both instructions to tags that the SCADA can write to.


And if you do that, don't make them "Constant" tags, or SCADA will not be able to write to them.