Hi, it appears that the U90 timers are different from the Vision timers.
While the vision timers have the Preset and Current stored in an Int32, the U90 timers are stored in an Int16 where the first 14 bits (LSB) are the value and the 2 MSBs are the resolution.
The Communication Driver fails on reading the timers preset/current on the Jazz or M90/91 PLC since it expects 8 characters and gets only 4 (this is why you get the exception of trying to part of strings out of its bounds)...
U90/91 and Jazz PLCs also does not support setting Current and Preset values using PCOM (while the Vision PLC does).
I'm not sure if this issue will ever get fixed.
Since Unitronics share the sources of the communication driver, then you can change the code in order to fix it, or you can use the SendString command in order to sent Read Timer Preset/Curremt commands to the Jazz PLC, and use the reply you got from the PLC in order to get its value. For example: