TI-505 PID problem

I don't understand your problem. It looks like it does what you want.

You can see in your example that when the PV reaches the SP the output drops back to 12ma which is what you desired.

It looks like your process is an integrating process (type 1) because the output can go back to a neutral value when the PV reaches the SP.

The example I gave is not a realtime simulation. My problem is that I dont think that the PLC will be giving an output of 12ma if I have:
SP=0
PV=0
output = ?
The first time the setup will be tried I dont think that the output will be 12ma

You can simply solve this problem by separating your PID control from your valve positioning (driving your output). At the end of your PID calculation take your PID output and other values that you require such at PV and SP and "cook up" your own output to drive your analogue output as you desire.

I use this sort of approach all the time particularly when I have a dual output PID where perhaps I want to bias the output to two
actuators. For example as North and South burners.

I've done similar things to get a pseudo split range control. Take the PID output and do some calculation on it, then send the results to two different control valves.