Controllogix 5000 Logic modification

Hi all,

I am new to the PLCs and need some help on a relatively simple task.
I would like to be able to manually introduce/force a bias to an analog value in the block portion of the logic.
I was going to use an ADD instruction with Source A = my original signal and Source B = bias.
Please help me understand something:
1. Is the easiest way to do it by creating a Tag, referencing it as input for Source B and using several MOV instructions (with several values I would like to introduce) with upstream (to that MOV) contacts and then forcing/toggling contacts on/off?
2. If I use a "constant" reference for Source B - is there a way to change/force different values (both + and -) online?
3. I can tie Source B to the output of several SELect instructions in series, is there an instruction I can use/force online as a ON/OFF switch?

TEST1, 2, 3 below correspond to the 1,2,3 questions above.

Any input would be greatly appreciated.

Depends what you are trying to achieve and how you can achieve it.

1) why add a pochle factor to an analog value in the first place? Lack of accuracy in the original value? Do you want to change what said analog value does in the program?
2) how do you want to trigger this extra value? External influences on a machine? Input from an HMI? Input directly via programming software? access only available to yourself?
3) do you want to change your extra value on the run? HMI input? Programming software?

Looks like any of your ways would work, depending on how you want to do it and how flexible the routine needs to be.