Rockwell Automation 1771-SDN DeviceNet Scanner Module Installation Instructions - Manual (Page 16)

Publication 1771-IN014B-EN-P - September 2001
16 DeviceNet Scanner Module Catalog Number 1771-SDN/C
How Your Module
Communicates with the
PLC-5 Processor The 1771-SDN scanner module uses four methods to transfer data,
status and command information between the scanner and the PLC-5:
•
DIO points for high-speed discrete outputs
•
DIO points for high-speed discrete inputs
•
BTW to send output data to the scanner
•
BTR to upload input data from the scanner
Using DIO Points for High-Speed Discrete Inputs and Outputs
The following table describes chassis addressing modes and the
number of discrete inputs and outputs assigned to the 1771-SDN
Scanner Module slot.
These inputs and outputs will appear in the PLC I/O image table in
the location corresponding to the rack, group and slot the module is
plugged into. Since the bits are in the I/O table, they can be forced.
For more information about chassis addressing modes, refer to your
PLC-5 processor system level installation manual.
Program Your PLC-5
Processor You must program your PLC-5 processor so it communicates with the
1771-SDN Scanner Module. Communication is possible when you
program your processor through multiple block transfer instructions.
The scanner uses the size of the block transfer to map the block
transfer data words into the scanner’s internal data table. The scanner
module accepts blocks of different sizes and knows that each block
has a different meaning.
PLC-5 block transfer instructions use one integer file in the data table
section for module location and other data to execute the instruction.
This is the control block file. The block transfer data file stores data
that you want to transfer to your module (when programming a block
transfer write (BTW)) or from your module (when programming a
block transfer read (BTR)). The address of the block transfer data file
is stored in the control block file.
You must select a separate data file for each of the block transfer
instructions. You must also use separate 5-word block transfer
Addressing Mode Discrete Inputs Discrete Outputs
1/2-slot 24 24
1-slot 8 8
2-slot 0 0