Rockwell Automation 1794-ID2 U.MNL INCREMENTAL ENCODER - Manual (Page 37)

Chapter
3
Publication 1794ĆUM015B-EN-P - May 2001
Programming Your
Incremental Encoder Module
To initiate communication between the incremental encoder module
and your PLC processor, you must enter block transfer instructions
into your ladder logic program. Use this chapter to enter the
necessary block transfer instructions into your ladder logic program.
To edit your ladder logic you See page
Enter Block Transfer Instructions . . . . . . . . . . . . . . . . . . . . . 3-1
PLCĆ2 Family Processors . . . . . . . . . . . . . . . . . . . . . . . . 3-2
PLCĆ5 Family Processors . . . . . . . . . . . . . . . . . . . . . . . . 3-2
SLCĆ5 Processors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3
The incremental encoder module communicates with the PLC
processor through bidirectional block transfers. This is the
sequential operation of both read and write block transfer
instructions.
Before you configure the module, you need to enter block transfer
instructions into your ladder logic. The following example programs
illustrate the minimum programming required for communication to
take place between the module and a PLC processor. These
programs can be modified to suit your application requirements.
A configuration block transfer write (BTW) is initiated when the
module is first powered up, and subsequently only when the
programmer wants to enable or disable features of the module. The
configuration BTW sets the bits which enable the programmable
features of the module, such as scalars and alarm values, etc. Block
transfer reads are performed to retrieve information from the module.
Block transfer read (BTR) programming moves status and data from
the module to the processor’s data table. The processor user program
initiates the request to transfer data from the module to the processor.
The transferred words contain module status, channel status and
input data from the module.
Your program should monitor status bits, block transfer read and
block transfer write activity.
What This Chapter
Contains
Enter Block Transfer
Instructions