RSLogix AOI Optional Inputs

[MMCC]

Hi,

Is there a way to know if an optional input is used? I am programming an AOI for customers. There are 2 inputs A and B. Input B is optional. If it is not set it should be set to A internally. If it is set then then value set must be used.

Is there a way to know that B was set? It could be any value so there is no way to use a dummy default.

Thanks!
Mark

 

[I_Automation]

If B = A when not used then add NEQ A B - - OTL B_Was_Used


Just add some way to unlatch the bit when you want to

 

[jridge]

You could do an input that enables input B. If it is disabled, set B to A.

 

[MMCC]

The application is an electric actuator is moving between 2 positions. The two moves could have separate speeds, accelerations, decelerations and torques. The AOI should use the move1 parameters if no move2 parameters are set. I am not sure how the NEQ A B would help.

 

[I_Automation]

B can probably be any POSITIVE value. At the end of the AOI after you have used B then MOV -999 B and at the start of the AOI check EQU B -999 OTE B_Is_Unused.



If that bit is off use B, if on MOV A B and use the A value in B until it is changed to -999. If -999 is a valid value you can go all the way down to -1.2 Billion for a DINT.


EDIT: I thought you just wanted to know if the 2 values were different, so I set a BOOL.

 

[MMCC]

Thanks I_Automation,

I will take a closer look at your suggestions (as well as jridge). Point is there is no clear method indicating how the user has used it and I have to work around what is available.

Thanks
Mark

 

[JeremyM]

Sure there is.

a) You can add another parameter to indicate which of the two are to be used. Same method could be used to select one of very many input parameters passed as an array (constant InOut).
b) Only ever pass 'A' or 'B' or ... or 'X' or 'Y' or 'Z', depending on what's happening in the calling code.

One downside to sanitizing a pass-by-ref parameter set as you're doing (B := A, if...) is that the calling code has no idea if (much less why) it changed.