S7-200 PID loop/EM235 problem

Hi guys I am new to this forum, recently I am having problem in configuring my PID loop. 4-20ma loop is used to measure pressure and setpoint is 100 pascal. I am using built-in PID wizard in Micro/win 4.0 and it's set to auto tune.

the problem is if pressure drops to zero, PID loop starts to integrate and output starts to climb, BUT it's not appearing on output terminals of EM235. even when AQW0 is set for 32000 I see only 3.6 volts across output terminals. the WEIRDEST thing is that IF I force 32000 to output (through status chart) i get the FULL voltage across terminals, but NOT when PID loop's output is 32000.

this is driving me crazy I tell you.

PV is AIW6
out put is AQW0

is there something I am missing to configure it properly or what!

Only time I have seen something similar was where I had two calls to a variable be it analogue output or register. MicroWin only displayed the first number it got to and so the value looked right but later in the program something else changed it. Compile the program and then check the cross reference list for a double entry both for AQW0 and the register in the PID table that controls AQW0.

I have had a faulty analogue module that had me confused for a while, its output wouldn't go to less than 1.5 volts but would go from there up to the full 10 volts. Your unit seems OK if you can force the output to the full range of values.

Good Luck

Bryan