1260-X133 User Manual
Module Operation 3-8
Racal Instruments
©
2005
1. Read the control register
2. Invert the bits (perform a one’s complement on the register
data)
3. Perform a bit-wise AND operation, leaving all but the
specific control register bit for the relay to change
4.
To open
: continue to step 5.
To close
: OR in the bit for the
relay to close.
5. Write the modified value back to the control register.
For example, to close channel 20:
1. Read Control Register 1 (this register controls 00, 800, 20,
40, 810 and 60 with channel 00 represented by the LSB)
2. Invert the bits in the value read in step 1
3. AND with 1111 1011 binary (the zero is in the position
corresponding to channel 20)
4. OR with 0000 0100 binary
5. Write the value to Control Register 1
The VISA I/O library may be used to control the module. The VISA
function
viOut8()
is used to write a single 8-bit byte to a control
register, while
viIn8()
is used to read a single 8-bit byte from the
control register. The following code example shows the use of
viOut8()
to update the 1260-X133 module.
Configuring
Larger
Multiplexers
The 1260-X133 is normally configured as twenty 1x4 multiplexers
and twelve 1x2 multiplexers. However, the plug-in contains special
configuration relays that interconnect four 1x4 multiplexers to form
a 2x8 matrix, and interconnect two 1x2 multiplexers to form a 1x4
multiplexer.
Figure 2-2 and Figure 2-4
shows these relays.
Table
3-1
provides the control register access information for these
relays.
As a configuration example, suppose you require the 2x8 matrix
X3, and a connection from input 2 of 4M2 to output of 4M3 (the
second 2x8 COL in
Figure 2-2
). You may form this path from a
1260-X133 by configuring it as follows:
1. Combine muxes 8, 9, 10 and 11 to form the 2x8 matrix X3.
