Rockwell Automation 1771-KA2 Communication Adapter Module - Manual (Page 16)

Station Hardware
Chapter 2
2-6
Figure 2.5
Module Indicators
COMM
ADAPTER
XMTG
RCVG
PROG
PROC
Message Ready
Transmitting
Receiving
Program Status
Processor Link
RDY
Status
XMTG
The green transmitting indicator turns on when the module is current
master of the Data Highway. When this indicator is on, therefore, the
communication adapter module is transmitting messages on the Data
Highway communication link, or it is polling.
RCVG
The receiving indicator turns on when the module is receiving a message
addressed to it. Otherwise, RCVG is off.
When both the RCVG and XMTG indicators are on, the module is current
master of the Data Highway and is polling. (The section titled “Polling,”
in chapter 8, describes polling procedure.)
RDY
The green message ready indicator turns on when the module has
messages ready to transmit. With this indicator on, the module is ready to
assume mastership when it is polled.