User manual

52 Using the Relay Multiplexer Chapter 2
Using the Analog
Bus
The multiplexer can be configured to perform voltage, two-wire ohm, or
four-wire ohm measurements using the analog bus. These measurements
can be performed by switching or scanning channels (refer to the previous
examples).
By switching the control relays (0990 to 0996), the COM lines can be
connected to the analog bus connection for measurement using a VXI
multimeter (such as the E1411B) or external multimeter (such as the
3457A). A special terminal enables the multiplexer to perform cable or
harness testing. You can connect the multiplexer analog bus to other
measurement or switching devices to perform measurements.
During a scan, the control relays (0992 to 0994 and 0996) are automatically
switched when configured using the SCAN:PORT command. See
[ROUTe:]SCAN:PORT on for more information.
When switching channels using the OPEN and CLOSe commands, the
analog bus must be manually connected. When the FUNCtion command is
executed, all analog bus control relays are opened. If an analog bus
connection is required, you must close the appropriate control relay. Once
switched, the relay remains closed unless specifically opened (OPEN
command, power-up, or *RST). Control relay numbers and functions follow.
• 0992: Connects lower 32 channels (banks 0 to 3) to the analog
bus H1 terminals.
• 0993: Connects upper 32 channels (banks 4 to 7) to the analog
bus H2 terminals.
• 0994: Connects lower and upper analog buses together (64
channel).
• 0996: Connects analog bus Guard (G) to the LO line on the upper
32 channels (banks 4 to 7).
Example: Connecting the
Analog Bus
In this example, as shown in Figure 2-9, the HI and LO terminals of bank 0
channel 0 are closed and the LO terminal of bank 4 channel 0 is closed
connecting them to their COM terminals. Control relays 0990 and 0991 are
automatically set open when configured for three-wire mode.
To connect bank 0 (both terminals) and bank 4 (LO terminal to Guard) to the
analog bus, control relays 0992 and 0996 must be closed. To connect bank
0 and bank 4 to the analog bus, execute:
CLOS (@10992,10996)
!Close control relay 0992 to connect bank

0-3 to the analog bus. Close control relay
0996 to connect bank 4-7 LO terminal to

the analog bus Guard terminal