FTview ME syntax error in expression

[bdoutney]

FactoryTalk view ME 8.1
Micrologix 1100
Panelview+ 600 = 2711P-T6C20D8
MER saved as 8.0

I am trying to write an expression for an alarm trigger that will be true when one bit is on(power on) and the other goes off(low level)

{::[PDS_2P+4P]B3:2/8}== 1 AND {::[PDS_2P+4P]B3:1/4} == 0 is not valid

{::[PDS_2P+4P]B3:2/8}== 1 AND {::[PDS_2P+4P]B3:1/4== 0} is valid but later the program says "no tag exists, would you like to create it"

{::[PDS_2P+4P]B3:2/8} AND {::[PDS_2P+4P]B3:1/4} this was valid and worked but only for the scenario of both bits being Hi.

 

[danatomega]

{::[PDS_2P+4P]B3:2/8} AND {::[PDS_2P+4P]B3:1/4} this was valid and worked but only for the scenario of both bits being Hi.

If you use OR instead of AND it should work when either bit is high.

 

[bdoutney]

I need the 1st one to be high and the second to be low

 

[danatomega]

Sorry, didn't fully examine the requirements...

You could try XOR is to see if it's valid.

Or, set it up as
(B3:2/8 AND NOT B3:1/4) OR (NOT B3:2/8 AND B3:1/4)

Or, you could do the logic in the PLC and the result bit gives you what you want without trying to wrangle the HMI to do the logic.

 

[bdoutney]

Sorry, didn't fully examine the requirements...

You could try XOR is to see if it's valid.

Or, set it up as
(B3:2/8 AND NOT B3:1/4) OR (NOT B3:2/8 AND B3:1/4)

Or, you could do the logic in the PLC and the result bit gives you what you want without trying to wrangle the HMI to do the logic.

Thanks, I know it would be easier in the PLC. Just started learning FT and trying to get the hang of expressions

 

[Operaghost]

Parenthesis......

( {::[SLC500]B3:2/8}== 1 ) AND ( {::[SLC500]B3:1/4} == 0 )

Make it solve the expression to the left of the AND before performing the AND. In your first example it solves the equation on the left then does the AND with B3:1/4 and it can't understand why you have the ==0 in the equation. Make it solve the expression to the left, then solve the expression to the right and only then perform the AND.



OG

 

[Kidblue]

Hi,

You could just use something like:

[Tag1] AND NOT [Tag2]

If you are conditioning at bit level you don't necessarily need to compare to 1 or 0 - they will be TRUE or FALSE by default.

Hope this helps,

Rob