5B02

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GENERAL DESCRIPTION

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

modules.

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.

Figure 2