Resetting the
Switchbox
This program resets the switchbox (relay or FET) by writing to bit 0 of the
Control Register.
!Convert the switchbox base address to decimal and store the value in a variable.
COM Base_addr
Base_addr=DVAL("1FDC00",16)
!Call the subroutine which resets the switchbox.
CALL Swbx_rst
END
!Subroutine which resets the switchbox by writing a 1 and a 0 to Control
!Register bit 0.
SUB Swbx_rst
COM Base_addr
OUTPUT 70900;"DIAG:POKE";Ba4;",16,1"
OUTPUT 70900;"DIAG:POKE";Ba4;",16,0"
SUBEND
Measuring the
Bridge Excitation
Voltage
This program closes internal channel 15 and tree switch 90 in order to
measure the bridge excitation voltage for a relay multiplexer switchbox.
!Convert the switchbox base address to decimal and store the value in a variable.
COM Base_addr
Base_addr=DVAL("1FDC00",16)
!Call the subroutine which measures the bridge excitation voltage.
CALL Ex_volt
END
!Subroutine which closes internal channel 15 in the Channel Register, and tree
!relay 90 in the Tree Switch Register in order to access (and measure) the
!bridge excitation voltage.
SUB Ex_volt
COM Base_addr
OUTPUT 70900;"DIAG:POKE";Ba8;",16,#H8000"
OUTPUT 70900;"DIAG:POKE";Ba6;",16,#H1"
SUBEND
FET Multiplexer
Scanning
This program makes
1
⁄
4
bridge strain measurements on three FET
multiplexer channels, using an external (HP 3458A) multimeter.
The program clears the FET multiplexer’s Scan Control Register,
downloads the scan list, sets the settling time, and then starts the scan. The
multimeter is connected to the multiplexer as indicated in Figure 2-8.
!Dimension computer variables to store the bridge output and bridge excitation
!voltages.
DIM Vout_unstr(1:3),Vout_str(1:3),Vr(1:3),Epsilon(1:3)
Appendix D
Strain Gage Register-Based Programming 135
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