Chapter 5
Programming
© National Instruments Corporation
5-9
SCXI-1100 User Manual
send a SCANCLK*-compatible signal on TRIG0. See Chapter 2, Configuration and
Installation, for more information. The module programming steps are as follows:
1. Perform any necessary programming to ensure that no modules are driving Analog Bus 0.
For an SCXI-1100, clearing AB0EN in the Configuration Register ensures that the register
output is not driving AB0.
2. Program the other module not to drive Analog Bus 0, but to send Analog Bus 0 to the data
acquisition board. Also program the other module to send a SCANCLK*-compatible signal
onto TRIG0.
3. Write the binary pattern
XXXGGGGG 01XCCCCC 00000111
to the SCXI-1100
Configuration Register, where
CCCCC
is the starting channel number.
Multiple-Module Multiplexed Scanning
To scan multiple modules, connect one module to the data acquisition board; the module must be
able to transfer Analog Bus 0 to the data acquisition board. This module must also be capable of
sending a SCANCLK*-compatible signal on TRIG0. See Chapter 2, Configuration and
Installation, for more information. The module programming steps are as follows:
1. Perform any necessary programming to ensure that no modules are driving Analog Bus 0.
For an SCXI-1100, clearing AB0EN in the Configuration Register will ensure that its output
is not driving AB0.
2. Program the module that is connected to the data acquisition board to connect Analog Bus 0
to the data acquisition board but not drive Analog Bus 0 unless it is receiving an active low
signal on SCANCON. Also program the other module to send a SCANCLK*-compatible
signal onto TRIG0. If this module is an SCXI-1100, write the binary pattern
XXXGGGGG
10XCCCCC 00000111
to its Configuration Register.
Note:
If this module is an SCXI-1100 and is not going to be scanned (it is being used only
as an interface), write a 0 to bit 2 (SCANCONEN) in the Configuration Register.
The gains and start channel become don't care bits.
3. Program the other modules to be used in the scan to connect their outputs to Analog Bus 0
but not drive Analog Bus 0 unless they are receiving an active low signal on SCANCON.
Also program the modules to use TRIG0 as their clock source. For SCXI-1100 modules,
write the binary pattern
XXXGGGGG 01XCCCCC 00000111
to their Configuration
Registers.
Multiple-Chassis Scanning
To scan modules on multiple chassis, you must use the SCXI-1001 chassis. The cable from the
data acquisition board must bus the digital lines to one module on each chassis. Additionally, the
cable must provide each chassis with its own analog channel. The data acquisition board must be
able to take several readings at a time on a given channel before accessing a new channel. See
the Counter 1 and SCANDIV subsection of the 1. Data Acquisition Board Setup Programming
section earlier in this chapter. You can use the MIO boards, along with the SCXI-1350
multichassis adapter, for multiple-chassis scanning.
For each chassis, program the modules according to the appropriate mode of operation,
disregarding the fact that other chassis are involved.
