Programming The Trigger Timer; Setting The Trigger Counter - HP E1419A User Manual

NOTE
Programming the
Trigger Timer
Setting the Trigger
Counter
80 Programming the HP E1419A
Parameter Value
BUS ARM[:IMMediate]
EXTernal " TRG" signal input on terminal module
HOLD ARM[:IMMediate]
IMMediate The arm signal is always true (scan starts when an
INITiate:... command is received).
SCP SCP Trigger Bus (future HP or SCP Breadboard)
TTLTrg<n> The VXIbus TTLTRG lines (n=0 through 7)
When TRIGger:SOURce is not TIMer, ARM:SOURce must be set to
IMMediate (the *RST condition). If not, the INIT command will generate
an error -221,"Settings conflict".
To set the external trigger signal as the arm source:
ARM:SOUR EXT
When the HP E1419A is triggered, it begins its algorithm execution cycle.
The time it takes to complete a cycle is the minimum interval setting for the
Trigger Timer. If programmed to a shorter time, the module will generate a
"Trigger too fast" error. So, how can you determine this minimum time?
After you have defined all of your algorithms, you send the ALG:TIME?
command with its <alg_name> parameter set to 'MAIN'. This causes the
HP E1419A's driver to analyze the time required for all four phases of the
execution cycle; Input, Update, Execute Algorithm, and Output. The value
returned from ALG:TIME? 'MAIN' is the minimum allowable Trigger
Timer interval. With this information you now execute the command
TRIGger:TIMer <interval> and set <interval> to the desired time that is
equal to or greater than the minimum.
The Trigger Counter controls how many trigger events will be allowed to
start an input-calculate-output cycle. When the number of trigger events set
with the TRIGger:COUNt command is reached, the module returns to the
Trigger Idle State (needs to be INITiated again). The default Trigger Count
is 0 which is the same as INF (can be triggered an unlimited number of
times). This setting will be used most often because it allows un-interrupted
execution of control algorithms.
To set the trigger count to 50 (perhaps to help debug an algorithm):
TRIG:COUNT 50
Source of Arm (after INITiate:... command)
trigger input on connector
module
execute algorithms 50 times then
return to Trig Idle State.
Chapter 3