Rockwell Automation DAG6.5.8 APPLICATION GUIDE SCADA SYSTEM - Manual (Page 86)

Publication AG-UM008C-EN-P - February 2005
3-18 Configuring MicroLogix 1100/1200/1500 Controllers
Monitor Active Stations
To see what slave stations are active when the channel is configured
for Standard Polling Mode (either single or multiple message per
scan), view the DF1 Half-Duplex Master Active Node Table. The table
is stored in the Communications Status Function File, words CSx:27 to
CSx:42, where x is the channel number (x=0 for MicroLogix 1100,
1200 and MicroLogix 1500 1764-LSP; x=1 for MicroLogix 1500
1764-LRP). Each bit in the table represents a station on the link, from 0
to 254, starting with CSx:27/0 for address 0 and CSx:42/14 for address
254. The bit for address 255 (CSx:42/15) is never set, since it is the
broadcast address which never gets polled.
When valid Normal and/or Priority Poll Ranges are defined:
•
if a slave responded the last time it was polled by the master, the
bit corresponding to its address is set (1=active).
•
if a slave did not respond the last time it was polled by the
master, the bit corresponding to its address is cleared
(0=inactive).
Undelivered Messages CSx:12 The number of messages that were sent by the controller but not
acknowledged by the destination device
Duplicate Messages
Received CSx:18 The number of times the controller received a message packet identical to
the previous message packet
Bad Packet Received CSx:16 The number of incorrect data packets received by the controller for which no
ACK was returned
Max Normal Poll List Scan CSx:20 Maximum time in 100 ms increments to scan the Normal Poll List
Max Priority Poll List Scan CSx:22 Maximum time in 100 ms increments to scan the Priority Poll List
RTS (Request to Send) CSx:9/1 The status of the RTS handshaking line (asserted by the processor)
CTS (Clear to Send) CSx:9/0 The status of the CTS handshaking line (received by the processor)
DCD (Data Carrier Detect)
(1) CSx:9/3 The status of the DCD handshaking line (received by the processor)
(1) Only present on the MicroLogix 1500 LRP channel 1.
(2) The channel number equals x.
Table 3.3 Understanding the DF1 Half-Duplex Master Status Screen Fields
Status Field Communication Status
Function File Location
(2)
Definition
TIP
The bit corresponding to the address configured for
the DF1 Master is always cleared because the master
address never gets polled.