Using The Scan Complete Bit - HP E1343A User Manual

Using the Scan Complete Bit

Example: Scan
Complete Interrupt
46 Understanding the Relay Multiplexer Modules
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You can use the Scan Complete Bit (bit 8) in the Operation Status Register
of a switchbox to determine when a scanning cycle completes (no other bits
in the register apply to the switchbox). Bit 8 has a decimal value of 256 and
you can read it directly with the
STATus:OPERation[:EVENt]?
When enabled by the
STAT:OPER:ENAB 256
Complete Bit will be reported as bit 7 of the Status Register. Use the HP-IB
Serial Poll or the IEEE 488.2 Common Command
Register. When bit 7 of the Status Register is enabled by the
Common Command to assert an HP-IB Service Request (SRQ), you can
interrupt the controller when the Scan Complete Bit is set, after a scanning
cycle completes. This allows the controller to do other operations while the
scanning cycle is in progress.
The following example monitors bit 7 in the Status Register to determine
when the scanning cycle completes. The computer used in the example is an
HP Series 200/300 used with HP BASIC as the program language. The
computer interfaces with the mainframe over HP-IB. The HP-IB select code
is 7, the HP-IB primary address is 09, and the HP-IB secondary address
is 14.
10 OUTPUT 70914;"*CLS"
20 OUTPUT 70914;"STAT:OPER:ENAB 256"
30 OUTPUT 70914;"*SRE 128"
40 OUTPUT 70914;"TRIG:SOUR EXT"
50 OUTPUT 70914;"SCAN (@100:115)"
60 OUTPUT 70914;"INIT"
70 WHILE NOT BIT(SPOLL(70914),7)
80 PRINT "DO OTHER OPERATION HERE" ! Enter program lines for
90 END WHILE
100 PRINT "INTERRUPT GENERATED"
110 END
STAT:OPER? command (refer to the
command in Chapter 5 for an example).
command, the Scan
*STB?
!Clear all switchbox status
structure.
!Enable Scan Complete Bit to set
bit 7 in Status Register.
!Enable bit 7 of Status Register
to assert SRQ.
!Set to external trigger mode.
!Select channels to be scanned.
!Start scanning cycle.
!Waiting for scan complete.
computer to do other operations.
!Program goes to this line after
interrupt is generated by a
completed scanning cycle.
to read the Status
*SRE 128
Chapter 4