FactoryTalk Expressions

[mcswc3]

I'm new to FactoryTalk and am struggling finding any information on using expressions.

1. How are you suppose to learn expressions - both correct syntax and know all what's possible to do?

2. Specifically:

I added:

IF {[PLC_1]Test_Tag_1} == 1
THEN 3
ELSE {[PLC_1]Test_Tag_2}

to the Multistate Button Indicator expression. State 3 on the button is the same button but "grayed-out" so the user sees the value but it's dull and the PLC won't do anything. And, it works! But, since I have to add this to a bunch of buttons, I was wondering if I could do something like:

IF {[PLC_1]Grayed_Out_Tag_1} == 1
THEN 3
ELSE DEFAULT

and "DEFAULT" would just use the tag that's already in the Value field...

Any suggestions would be much appreciated!

 

[dcooper33]

I'm new to FactoryTalk and am struggling finding any information on using expressions.

1. How are you suppose to learn expressions - both correct syntax and know all what's possible to do?

2. Specifically:

I added:

IF {[PLC_1]Test_Tag_1} == 1
THEN 3
ELSE {[PLC_1]Test_Tag_2}

to the Multistate Button Indicator expression. State 3 on the button is the same button but "grayed-out" so the user sees the value but it's dull and the PLC won't do anything. And, it works! But, since I have to add this to a bunch of buttons, I was wondering if I could do something like:

IF {[PLC_1]Grayed_Out_Tag_1} == 1
THEN 3
ELSE DEFAULT

and "DEFAULT" would just use the tag that's already in the Value field...

Any suggestions would be much appreciated!

Hi and welcome to the forum!

Try this manual, chapter 23 specifically, it will tell you all you need to know about using expressions. Also, there is a syntax checker in the expression field, which will tell you if your syntax is "correct". Actually, all it can tell you is if your syntax is executable, but not necessarily if it will do what you want it to!

In answer to your question, I don't believe you can do what you're asking inside the expression for the value of the multi-state. The software does not recognize "DEFAULT".
You could perhaps do something like this:

IF {[PLC]Test_Tag} == 1 THEN 3
ELSE {[PLC]Default_Tag}

Then have the PLC continually write the value of the tag in the indicator into "Default_Tag".

Cheers,
Dustin

 

[mcswc3]

Thanks for the manual -- I'll check that out.

Any way to maybe use the Error state of the button?

IF {[PLC]Test_Tag} == 1 THEN ERROR
ELSE {[PLC]Default_Tag}

 

[dcooper33]

Thanks for the manual -- I'll check that out.

Any way to maybe use the Error state of the button?

IF {[PLC]Test_Tag} == 1 THEN ERROR
ELSE {[PLC]Default_Tag}

Hmm I've never tried that, but yeah you probably could.

 

[mcswc3]

Starts in state 0, push the button once = output is fired (state 1), push the button twice = nothing happens (state 2), push the button a third time = back to state 0.

So maybe instead of using the error state, I should have asked if there is a way for the button to ignore state 2 when it's not grayed-out.

IF {[PLC_1]Test_Tag_1} == 1 THEN 2
ELSE {[PLC_1]Test_Tag_2} == 0 OR 1

is allowed, but does not restrict {[PLC_1]Test_Tag_2} to a 0 or 1 state...

 

[mcswc3]

Ended up making the Error state of the button a grayed-out version of the actual button and used the expression below. Works great. Thanks for your help!

IF {[PLC]System_In_Auto} == 1
THEN {[PLC]NOT_AN_ACTUAL_TAG_SO_TRIGGERS_ERROR_STATE}
ELSE {[PLC]Manual_Function}