Allen Bradley Timers

[taylorICS]

Hi Guys

Got an easy one for the experts. I'm new to RSLogix and Allen Bradley and I want to set a timer value via a HMI. I would do this by writing a constant value to say N7:0. However the 'Preset' word only takes a constant and won't accept N7:0. I'm use to Mitsi where you can just assign a Data Register to the timer. How is it done in Allen Bradley?

Cheers

 

[ianingram]

Use the MOV instruction...

For example
Source N7:0
Destination T4:0.PRE

 

[taylorICS]

Cheers for that seems so simple now lol

 

[Mickey]

It's also a good idea to check the value from your HMI for limits before moving it to the timer preset. The "LIM" limit instruction works well for this.

 

[daba]

It's also a good idea to check the value from your HMI for limits before moving it to the timer preset. The "LIM" limit instruction works well for this.

Mickey makes a good point but fails to say why....

Allen-Bradley timers have a heart attack with negative PRE or ACC values - major fault....

Sometimes HMIs and PLCs don't speak the same numerical language, and putting LIM checking in is necessary to stop a PLC from red-light faulting.

Min/Max values for A-B timer presets.....

PLC5/SLC - 0, 32,767
Logix5000 - 0, 2,147,483,647

Any value above the "max" quoted above is seen as a negative value, so the PLC will fault/stop