User`s guide

Chapter 3 To Use External DMM RIGOL
M300 User’s Guide
3-5
Scan Control Method
The typical scan control method based on the connection shown in Figure 3-1 is as
follows.
1 After the external DMM and M300 are connected and configured properly, press
the Run/Stop key at the front panel of M300 to place M300 into “wait for
trigger” state.
2 When the preset trigger condition of the scan list is reached, the first channel in
the scan list is closed. At this point, the pin 5 (Channel Closed Output) of the
Alarm/Ext Trig interface outputs a negative TTL pulse (its pulse width is about
7μs and its output speed is related to the measurement speed and can not
exceed 1000 times per second) to the external trigger input interface and then
the external DMM starts measuring.
3 When the measurement is finished, the VMC (Voltage Measurement Complete)
output interface of the external DMM outputs a negative TTL pulse with about
2μs pulse width to the pin 6 (Channel Advance Input) of the Alarm/Ext Trig
interface. Thus, M300 open the first channel and close the next channel. At this
point, the pin 5 of the Alarm/Ext Trig interface outputs pulse again to control the
external DMM to start measuring.
Then running down accordingly, all channels in the scan list are scanned.