© National Instruments Corporation
5-1
SCXI-1160 User Manual
Chapter 5
Programming
This chapter contains a functional programming description of the SCXI-1160 and Slot 0.
Note: If you plan to use a programming software package such as NI-DAQ, LabWindows, or
LabVIEW with your SCXI-1160 board, you do not need to read this chapter.
Programming Considerations
Programming the SCXI-1160 involves writing to the Data Register. Programming the data
acquisition boards involves writes to their registers. See your data acquisition board user manual
for more information. The programming instructions list the sequence of steps to take. The
instructions are language independent; that is, they instruct you to write a value to a given
register without presenting the actual code.
Notation
For the bit patterns to be written, the following symbols are used:
0
binary zero
1
binary one
X
don't care; either zero or one may be written
The bit patterns are presented MSB first, left to right.
Register Writes
This section describes how to write to the Data Register including the procedure for writing to
the Slot-Select Register to select the appropriate slot. For timing specifics, refer to the Timing
Requirements and Communication Protocol section in Chapter 2, Configuration and Installation.
The rear signal connector pin equivalences to the different National Instruments data acquisition
boards are given in Table 5-1. See also Appendix E, SCXI-1160 Cabling. The Data Register is a
write-only register.
The different bits in this register control independent relays. There are times when you may
want to set or reset a specific relay or relays without affecting the remaining relays. However, a
write to the Data Register affects all relays simultaneously. You cannot read the register to
determine which relays have been set or reset in the past; therefore, you should maintain a
software copy of the relay states. You can then read the software copy to determine the status of
the relays. To change the state of a single relay without disturbing the remaining relays, change
the bits that control the relay coils of interest, clear all other bits (no change in states), and
rewrite to the Data Register.