Model 5B02 Backplane - The 5B02 diagrammed in Figure 1, is
a 16 channel backplane. It incorporates input and output buses
that take advantage of the internal series output switches in the
input modules and the track-and-hold in the output module.
Designers integrating the 5B02 into a measurement and control
system do not need external multiplexers and can use a single
digital-to-analog converter to server numerous output channels.
Digital outputs from the host data acquisition system are used
to address the 5B Series modules and designate inputs and
outputs. Only one analog input, one analog output, and a
number of digital outputs are required to address up to 64
analog input/output channels.
Model 5B02 System Connectors – Signal connections between
the 5B02 backplane and the associated measurement or control
system are made at P1. One signal path is provided for inputs
and one for outputs. Input and output modules are
independently addressed by two sets of six address pins and an
enable pin. In addition, a number of grounded pins are present
in the connector pin-out to provide shield conductors in the
ribbon cable. In some cases, discussed below, the ground
conductors will not provide an accurate signal reference, so a
SENSE pin is also provided in the pin-out. Several jumper and
component options in the backplane provide optimum ground
connections for various circumstances.
Model 5B02 Grounding – Each 5B02 backplane is factory
configured with Jumpers W1, W2, and W4 installed. Jumper W1
grounds the shield wires in the ribbon cable (Pins 2,5, and 6) at
the 5B02 backplane. This will usually be the primary ground
connection between the 5B02 and the measurement system.
This connection is required if output modules will be used on
the backplane. It is also required if there is no high impedance
sense input (input low of a differential or pseudo-differential
system) available on the measurement system. Jumper W2
connects the sense input, if available, to Pin 25 so that the 5B02’s
ground is read. It can be left in place at all times. Jumper W4
connects +5 VDC power common to input/output common
(backplane measurement ground). A connection between
power common and input/output common is important for the
5B Series modules to function properly; however, if this
connection is made elsewhere in your system (the best place is
usually near the A/D or D/A converters), W4 should be cut
since a ground loop could result.
Model 5B02 Address Selection Jumpers – The 5B02 backplane
can hold 16 modules in any combination of inputs or outputs.
Address decoders on the backplane (separate decoders are
provided for inputs and outputs) determine which module is
read (inputs) or driven (outputs). To permit system expansion,
up to four backplanes can be daisy-chained on the system I/O
ribbon cable for a total of 64 channels. Jumpers on each
backplane (labeled SH1-5 and SH6-10) determine the block of
16 addresses assigned to each backplane. Input (read) and
output (write) addressing are completely independent; in all
cases, Jumpers 1-5 control inputs and 6-10 control outputs.
Independent addressing might be used, for example, to update
output modules without interrupting the monitoring of input
Backplanes are factory configured with jumpers at Positions 1
and 6. This sets up the backplane as a stand-alone 16 –channel
system; the two highest order address bits in the read and write
addresses are ignored. Moving the jumpers to any other
position in the two blocks enables decoding of the full six
address bits. The exact position of the jumper determines
address position for the backplane. To use multiple backplanes
in this manner, connect the corresponding I/O connector pins
of each backplane in parallel. CAB-01 is a ribbon cable with
three 28-pin connectors designed for this purpose.
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