HP FET MULTIPLEXER E1351A/53A manual Using the Scan Complete Bit, Example Scan Complete Monitor

Using the Scan Complete Bit

You can use the Scan Complete Bit (bit 8) in the SCPI Operation Status Register 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 STAT:OPER? command (refer to the STATus:OPERation[:EVENt]? command in Chapter 5 for an example). Note that this is not the same register as the multiplexer Status/Control Register.

When enabled by the STAT:OPER:ENAB 256 command, the Scan 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 *STB? to read the Status Register. When bit 7 of the status Register is enabled by the *SRE 128 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.

Example: Scan

Complete Monitor

10	OUTPUT 70914;"*CLS"	!Clear all switchbox status
		structure
20	OUTPUT 70914;"STAT:OPER:ENAB 256"
		!Enable Scan Complete Bit to set
		bit 7 in Status Register
30	OUTPUT 70914;"*SRE 128"	!Enable bit 7 of Status Register to
		assert SRQ
40	OUTPUT 70914;"TRIG:SOUR EXT"	!Set to external trigger mode
50	OUTPUT 70914;"SCAN (@100:115)"	!Select channels to be scanned
60	OUTPUT 70914;"INIT"	!Start scanning cycle
70	WHILE NOT BIT (SPOLL(70914),7)	!Waiting for scan complete
80	PRINT "DO OTHER OPERATION HERE"
		!Enter program lines for computer
		to do other operations
90	END WHILE

100PRINT "INTERRUPT GENERATED" !Program goes to this line after interrupt is generated by a completed scanning cycle

110 END

52 Understanding the HP E1351A/53A FET Multiplexer Modules Chapter 4