Chapter
3
Publication 1794-6.5.16 – September 1998
To initiate communication between the Pulse Counter 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
PLC-2 Family Processors . . . . . . . . . . . . . . . . . . . . . . . . 3–2
PLC-5 Family Processors . . . . . . . . . . . . . . . . . . . . . . . . 3–2
SLC-5 Processors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3–3
The Pulse Counter 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
Allen-Bradley HMIs