5
Pulse Concepts and Pulse Generator Operations
5.1 Counter Architecture Overview
*Start source is:
Run/Stop button/function in Internal Modes
External input in External Trigger modes
*TRG command via Serial access
**Channels are armed by the Run/Stop function (external button or through 525 application). In
single shot and burst modes channels may be rearmed by pressing the RUN button again.
5.2 System Timer Functions
The System Timer functions as a non-retriggerable, multi-vibrator pulse generator. This means that once
started, depending on the mode, the timer will produce pulses continuously. Before pulses can be generated,
the timer must be armed and then receive a start pulse. Arming the counter is done by enablin g the Run/Stop
function by either the external button or through the 525 application. With external trigger disabled, the
Run/Stop function also generates the start command for the counter. With external trigger enabled, the
external trigger provides the start pulse. In either case, once started, the counter operation is determined by
the System Mode Generator. Standard modes include:
Continuous
Once started T
0
pulses are generated continuously.
Single Shot
One T
0
pulse is generated for each start command.
Burst
„N‟ T
0
pulses are generated for each start command.
Duty Cycle
Once started T
0
pulses cycle on and off continuously.
The
T
0
pulse is distributed to all of the start inputs of the Chan nel Timers and Mode Generators.
5.3 Channel Timer Functions
The Channel Timer functions as a non-retriggerable, delayed, one shot pulse generator. This means that the
timer will only generate one delayed pulse for every start pulse received. Once the channel timer has started
counting, additional start pulses will be ignored until the pulse has been completed (non -retriggerable). The
start pulse for each channel is provided by the internal T
0
pulse generated by the internal system timer.
Whether or not a pulse is generated for each T
0
pulse is determined by the Channel Mode Generator.
