Modicon PID2..negitive low engineer range

OK..so i have a PID2 block controlling a valve, this valve opens and closes to keep water coming out of a cooler at 2 deg c..

I have a 0-100 deg RTD,

In the PID block at 4x +12 i have to put in the low engineer unit.. in the case of the RTD i have now it is 0, However how would i handle it if it is a -100 to +100 RTD? The PID block wont take a negative number..

There must be some work around trick but im drawing a blank right now..


Thanks

Darren

Sorry...momentary brain ****...

Instead of scaling i just put in 4095 as the max unit and use the raw values.....