User manual

Publication 1797-6.5.1 - April 1999

Appendix

Programming the FLEX Ex I/O Modules

Using RIO

What this Chapter Contains

Read this appendix to program the 1797-IE8 and 1797-OE8

analog modules.

Enter Block Transfer

Instructions

The FLEX Ex analog I/O modules communicate 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 analog

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

filters and signal ranges, 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.