Rockwell Automation 1771-OFE/B Analog Output Module User Manual - Manual (Page 51)

Chapter
5
Publication 1771Ć6.5.30 - November 1998
Module Status and Input Data
In this chapter, you will read about:
For information on See page
ReadingData from the Module . . . . . . . . . 5-1
Block transfer read (BTR) programming moves status and data from
the module to the processor’s data table in one I/O scan. 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. The maximum BTR data file length
required is five words.
Figure 5.1
Word Assignment for Block Transfer Read
Decimal Bit 15 14 13 12 11 10 09 08 07 06 05 04 03 02 01 00
Octal Bit 17 16 15 14 13 12 11 10 07 06 05 04 03 02 01 00
Word 1 Channel 1 DAC Input Data
2 Channel 2 DAC Input Data
3 Channel 3 DAC Input Data
4 Channel 4 DAC Input Data
5
Not
used
I/O
Reset
Reserved Data Valid
Important: The user program that uses the read block transfer must
make sure that Bits 06 and 07 (the write enable and read
enable request bits) of the MCB are not set
simultaneously.
What This Chapter
Contains
Reading Data from the
Module