EX timing was reporting error with 4th Duotone slave, and h1iopiscex was in error. I found that the timing slave on h1iscex's IO Chassis was still trying to sync up (flashing LED). This system has a separate DC power supply for the timing slave, part of a past noise study. I power cycled both the timing slave and the IO Chassis, and now the code is running correctly and the timing error has been resolved.