arrel produced the 1st version of the PID code to drive just one channel. I then compiled and ran it to see how it performed. Over the course of several evenings I managed to get the values tweaked enough to maintain a stable temperature that would drift no more than 0.5 a degree in the course of the evening.

Armed with the feedback, DT then went on to work on multiple channel PID loops, and after a few weeks of frantic PM's between him and Henrik came back with some further code for me to test and try. The result was that after some further tweaking at my end, we managed to have 4 independent channels all running at the same time and in the test rig, maintaining a constant temperature.