Rockwell Automation 1771-DA,D17716.5.13 U MNL 1771-DA ASCII I/O MODULE - Manual (Page 136)

Chapter
6
6Ć1
Function of Control and Status Bits
In this chapter you will read about control bits found in command word
one and in four initialization words. You will also read about status bits
found in status words one and two.
The first two words in every write block transfer are command words.
Command word one contains control bits. Command word two is set to
zero and is reserved for future enhancements. The bits in command word
one (CW1) are as follows.
Command Word One, CW1
Bit: CW1(00)
Function: Reserved for Future Use
Description: Reset this bit to zero.
Bit: CW1(01)
Function: Reserved for Future Use
Description: Reset this bit to zero.
Bit: CW1(02)
Function: Reserved for Future Enhancements
Description: Reset it to 0.
Bit: CW1(03)
Function: Resets input buffer full bit.
Description: Set this bit to reset status bit 03, input buffer full, in status
word one. This turns off the BUFFER FULL LED indicator. Otherwise,
reset this bit to zero.
Bit: CW1(04-06)
Function: Reserved for Future Enhancements
Description: Reset it to zero.
Bit: CW1(07)
Function: Resets power-up and handshaking bits.
Chapter Objectives
Command Words