Right now the TRiLOGI does not implement the change of timer and counter set value in its "Edit variable" interface as the change is not immediately visible on the online monitoring screen. So to prevent changing the timer/counter value by mistake which can lead to problem, timer/counter cannot be changed from TriLOGI online monitoring.
However, you could use the host link command "Wm" and "Wu" you can change the timer or counter set value through TLServer "Serial Port Setup" screen. That means user's own application program written in VB6 or VC++ can change the timer/counter SVs via the serial command.