Your basic architecture is not set up to allow changes (Volts/Ohms/Amps) after the program is started.
You wait until the user clicks one of those and then you don't pay attention any more.
Usually, you want the EVENT structure to be INSIDE the WHILE loop.
When an event happens, you handle it, and then loop back for another event.
In this case, I would have a TIMEOUT event, so that you can check the serial port every X mSec,
Something like this:
Repeat {while loop }
case EVENT of
VOLTS button - Value Change:
Send command for VOLTS mode to instrument
Shift Register = 0 (VOLTS mode)
OHMS button - Value Change
Send command for OHMS mode to instrument
Shift Register = 1 (OHMS mode)
AMPS button - Value Change
Send command for AMPS mode to instrument
Shift Register = 2 (AMPS mode)
TimeOut:
if Incoming Data
Process data into numbers.
case Shift Reg of
0: Pass number to VOLTS chart
1: Pass number to OHMS chart
2: Pass number to AMPS chart
default: do nothing
end case
end if
Stop Button - Value Change
Stop Loop
end case
until Stopped (end loop)
