Discrete Value is a Signed Integer


I’m new to the Opto22 world and in trying to familiarize myself with how it works I had a question. When using PAC Display I set up a simple switch that toggles back and forth. I assigned a numeric variable to the resulting value. When the switch is off, the variable is set to 0 but when it’s on the value is set to -1. I know I can use the Absolute function to remove the sign but why doesn’t it just give me a 1?

Thanks in advance.


Good news, this is a configurable setting. The default is -1 but you can change it to +1 in PAC Display Config, select Configure > Runtime… then you’ll see a checkbox for “Send +1 for Discrete Integer Writes.”

Ta-da! As far as “why” the default is -1, that’s another story, and I have a whole post on “what is ‘true’?” but I suspect that’s more info that you really want…


You’re the best, Mary! Thank you! The more I work with the SNAP-PAC system, the more I like it and your support is terrific.

Actually that’s not more info than I want. :-} Post the link, if you would. I’d like to take a look at it.



Below find link to that “what’s true” post I mentioned, but reading over it now I realize I didn’t talk about why. (Short answer: -1 was “true” back w/our older products, and we like to make your transitions to new hardware as easy as possible, even though we’re becoming even more “positive” as we mature…)
Anyway, thanks for the kind words!!! Here’s the TMI, since you asked…


Interesting. Some good tips there. In my case I’m writing to a modbus device which needs either a 1 or a 0 turn turn a valve on and off. It ignores everything else.