PID on fx2n plc

I am writitng a PID instruction on the Fx2n plc and was wondering about integral windup when I write my own PID instruction I clamp the I term so wind up doesent occur but with PID in the PLC i cant see how to clamp it or do ineed to with this instruction any info on this would be great.

Thanks In Advance

Liam

The easy thing to to is to stop integrating when the output is saturated.

If the output reaches + or - 10 volts stop integrating. This requires a simple check before updating the integrator term.

Peter thanks for the reply. The problem I think I have is I dont think I can clamp the I term I, with the in built PID instruction in GX developer. Theres no register shown in the manual for that .I can clamp the controller output alright M. If I was was writing the PID loop manually then I would have full control over the P I and D and I could clamp I so wind up would not occur.

This is the PID Instruction

---[PID s1 s2 s3 s4]-----

---[PID D100 D200 D300 D400]---

where s1 = set point
s2 = current value say level of liquid in a tank
s3 = takes 25 consective registers for the PID instruction
s4 = PID controller output

See attached screen shot from the manual with the registers used for the PID instruction.

Really my question is how is integral wind up looked after in the instruction if i can not access I.