Changing parameters in the SCL instruction

Hello,

Is it possible to change the parameter in the max scaled value line in the SCL instruction for RSLogix 500 automatically?

I have a 4-20ma input signal from a speed sensor that is scaled. What I'd like to do is if the speed reaches x rpm then I want to change the value in another SCL instruction that will then slow the motor back down. I would the PLC to automatically monitor the speed and have it adjust itself to keep the motor from going to fast and or stoping. Its more of a saftey, incase something goes wrong and the process doesn't need to completely stop but yet get back on track and correct itself.

Thanks John

if I understand what you're asking (and I think I do) then try using a memory location (example: N7:0) for the entry instead of a specific number ...

I actually thought of trying that. Instead of a max scaled value of 2500 I could try to insert N7:3 etc.. and the use a GEQ instruction to change the value of N7:3. I was going to try it, but I wanted to check to see if anyone has done such a thing. I don't like thoughs little Fatal Error messages on my screen.

Thanks I'll try it.

John

it's done quite often ... now if you want to prevent errors and things like that, you might want to look into "limiting" the value in the memory location to a range of "good" values just before the SCL executes ... this is usually done with two rungs ... one has an LES and an MOV ... the other has a GRT and an MOV ... ask if you need more help than that ...