I work at a Bio tech company in Ma. We manufacture a Feline Leukemia Virus vaccine. We currently use a TCS 6366 controller(1987 vintage) to control our pH in our 500 L fermenter. The 6366 controller has been giving us some erratic out puts. We would like to program another 6366 as a backup so we can service the failing controller. In order to program the controller we have to use a 486 PC running win 3.1 using an RS232 interface to the front of the controller. We have not had any success programing a backup controller. The program that gets uploaded to the controller is written in programming language FOURTH. Those of us working on this problem believe that there is a problem with the FOURTH program or the parameter file that loads with it. We have loaded other programs on to the controller with success (agitation and temp control). I will be attaching the two fourth files with this post. If anyone has any suggestions on the program logic or parameter files your thoughts would be greatly appreciated.