Getting Started 37Chapter 1
Programming the Switch
This section gives guidelines and examples to program the E1442A
64-Channel Form C switch module using Standard Commands for
Programmable Instruments (SCPI), including:
•Specifying SCPI Commands
•Start-up Exercises
Specifying SCPI
Commands To program the E1442A switch using SCPI, you must select the computer
language, interface address, and SCPI commands to be used. Guidelines
to select SCPI commands for the switch follow.
NOTE This discussion applies only to SCPI programming using the switch box
driver version provided with this module. See Appendix B for infor mation
on register-based programming of switch registers.
To address specific channels within a switch, you must specify the SCP I
command and switch channel address. For the Form C switch, use CLOSe
<FKDQQHOBOLVW> to connect the normally open (NO) terminal to the common
(C) terminal for the channels specified.
Use OPEN <FKDQQHOBOLVW> to connect the normally closed (NC) terminal
to the common (C) terminal for the channels specified. Use SCAN
<FKDQQHOBOLVW> to close the set of channels specified, one channel at a time .
The Normally Open (NO) contact of each Form C relay is "open" and the
Normally Closed (NC) contact of each Form C relay is "closed" when the
switch is deactivated (the Common terminal (C) is connected to NC a t
power-on, after reset or after an open command).
Card Numbers The switch card number depends on the switchbox configuration (single-
module or multiple-module) set for the switches. Leading zeroes can be
ignored for the card number. See "Setting Logical Address" in this
chapter for more information on setting logical addresses and swit chbox
configurations.
For a single-module switchbox, the card number is always 01. For a
multiple-module switchbox, the card numbers are 01, 02,...,nn. Th e module
with the lowest logical address is card number 01, the module with the n ext
lowest logical address is card number 02, etc.
For example, assume three Form C switches are configured to form a
multiple-module switchbox instrument with logical addresse s of 120, 121,
and 122 as shown in Figure 1-24. Since card number 01 is assigned to the
module with the lowest logical address, card number 01 is assigned to the
card at logical address 120. Card number 02 is assigned to the card at
address 121 and card number 03 is assigned to the card at address 122.