Avtech AV-1011-C-OP1 Instructions Manual page 21

OP-1 Operating Instructions
For example, for a GPIB controller from National Instruments, the following set of
commands would be sent:
ibwrt "r=1000"
ibwrt "w=30"
ibwrt "v=30"
ibwrt "a=10"
ibwrt "P=+"
This command sequence will cause the generator to produce a series of positve
output pulses of width 30 micro-sec and an amplitude of 30 volts peak, repeated at a rate
of 1000 pulses per second. An oscilloscope attached to the generator output will confirm
the result. If the generator output trigger port is used, it will be noted that each output
pulse will be delayed 10 micro-sec after the trigger pulse occurs.
2.4 Sample Program
To illustrate the remote control process by means of the GPIB, a sample program
written in BASIC is provided. While this example is prepared for use with the B&C
MicroSystems PC488 circuit card, the general principles of control apply to any IEEE 488
GPIB Controller.
'TEST of Pulser Controller
OPEN "PC488" FOR OUTPUT AS #1
PRINT #1, "ABORT"
PRINT #1, "CLEAR"
PRINT #1, "OUTPUT 8;V", 30
PRINT #1, "OUTPUT 8;W", 30
PRINT #1, "OUTPUT 8;R", 1000
PRINT #1, "OUTPUT 8;A", 10
PRINT #1, "OUTPUT 8;P", +
END
3.0 Duty Cycle Limits
Typically, Avtech pulse generators are limited to a maximum duty cycle because of
thermal constraints, where duty cycle is the ratio of Pulse Width to the reciprocal of the
Repetition Rate (i.e.; R times W). Although the generator contains automatic protection
against an excessive duty cycle, whenever this protection is activated, the output is
inhibited. Therefore, it may be desirable to have the control computer calculate the duty
ratio, then generate a warning message to the operator whenever the limits are exceeded
(preferably prior to actually sending the command sequence).
This message could caution the user either to reduce the repetition rate or the
pulse width, to avoid thermal overload.
While this calculation is not mandatory, it could avoid the annoyance of automatic
inhibiting of the generator output.
2/8/96 3 AN-101-1011