1260-X138 User Manual
Racal Instruments
©
2005
Module Operation 3-9
this, we must close the relay shown as “K1” in
Figure 2-2
.
Referring to
Table 3-1
, we see that bit 0 of control register
0x01D controls this configuration relay. To combine the
multiplexers, write to the register to set this bit (leave the
other bits unchanged).
2. Combine multiplexers 2, 3 and 4 to form a 1x24 multiplexer.
To do this, close the “K3” and “K79” configuration relays (in
Figure 2-1
). From
Table 3-1
we see that the “K3” relay is
controlled by bit 2 of control register 0x01D. Also, bit 3 of
control register 0x01D controls the “K39” relay. Set both of
these bits (without changing any other bits).
Creating Very
Large
Multiplexers With
the Analog Bus
The 1260-X138 has access to the analog bus of the 1260-100X
Carrier. The analog bus can connect multiplexer group of one 1260-
X138 to multiplexer group of another 1260-X138, providing endless
possibilities for creating large multiplexers from two or more plug-
ins.
The analog bus consists of four two-wire paths, numbered as ABUS
0 through ABUS 3. These paths are accessible from a 1260-100X
X-series Adapt-a-Switch Carrier slot. To link multiplexer group of
one 1260-X138 to multiplexer group of another 1260-X138, we
must connect them both to the same analog bus path.
For example, suppose you wish to create a 1x128 multiplexer. This
requires two 1260-X138 plug-ins. To configure them as a single
1x128 multiplexer, proceed as follows:
1. Configure the first 1260-X138 as a 1x64 multiplexer. To do
this, close the following configuration relays (shown in
Figure 2-1
):
K1, K2, K3, K79, K80, K81 and K113.
Table 3-1
indicates the registers and bit positions used to
control these relays. Setting a bit to 1 closes the relay.
2. Configure the second 1260-X138 as a 1x64 multiplexer.
Close the following configuration relays (shown in
Figure 2-
1
):
3. K1, K2, K3, K79, K80, K81 and K113
4. Next, we connect both of these 1x64 multiplexers to the
same analog bus path, forming a single 1x128 multiplexer.
Close the “ABUS 3” relay K112 on the first plug-in. Referring
to
Table 3-1
, we see that this relay is controlled by bit 3 of
control register 0x021. Set the bit to 1 to close the relay.
