Power Meter Remote Operation
Status Reporting
EPM-P Series Power Meters Programming Guide
1-81
The SRQ Method
When a bit of the Status Register is set and has been enabled to assert
SRQ (
*SRE
command), the power meter sets the GPIB SRQ line true. This
interrupt can be used to interrupt your program to suspend its current
operation and find out what service the power meter requires. Refer to
your computer and language manuals for information on how to program
the computer to respond to the interrupt.
To allow any of the Status Register bits to set the SRQ line true, you must
enable the appropriate bit(s) with the
*SRE
command. For example, if
your application requires an interrupt whenever a message is available in
the output queue (Status Register bit 4, decimal weight 16). To enable
bit 4 to assert SRQ, use the command
*SRE 16
Note
You can determine which bits are enabled in the Status Register using
*SRE?
. This command returns the decimal weighted sum of all the
bits.
Procedure
• Send a bus device clear message.
• Clear the event registers with the
*CLS
(clear status) command.
• Set the
*ESE
(standard event register) and
*SRE
(status byte register)
enable masks.
• Enable your bus controller’s IEEE-488 SRQ interrupt.
Examples
The following two examples are written in HP BASIC and illustrate
possible uses for SRQ. In both cases, it is assumed that the meter has been
zeroed and calibrated.
Example 1:
10 ! Program to generate an SRQ when a channel A sensor
20 ! connect or disconnect occurs
30 !
40 ASSIGN @Pm TO 713
! Power meter GPIB address
50 ON ON INTR 7 GOTO Srq_i! Define service request handler
60 CLEAR @Pm ! Selective device clear
70 OUTPUT @Pm;”*CLS;*RST” ! Clear registers and reset meter
80 !
90 ! Configure the device status register so that a sensor
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