Rockwell Automation 1785-Lxxx Enhanced and Ethernet PLC-5 Programmable Controllers - Manual (Page 166)

Publication 1785-UM012D-EN-P - July 2005
10-16 Communicating with Devices on a Serial Link
To define a polling scheme using standard mode, you must specify the
following on the DF1 master configuration screen in your programming
software:
The master station polls the slave station in the following a
definitive sequence:
1. All stations in the active priority poll file.
2. Specified stations in the active normal poll file. The number of stations
polled in this file is determined by the normal poll group size specified
on the configuration screen. If the group size was 3, for example, then
three stations would be polled in the normal file before the master
continues to the next step in the sequence.
3. One station in the inactive poll file after all active stations in the normal
poll file have been polled.
Configuration Parameter Definition
Polling mode How you want the master to poll the station lists.
Master message transmit When you want the master to send messages.
Normal poll file An integer file in which you place the station addresses of
the remote stations.
The default size is 64 words.
Priority poll file An integer file in which you place the addresses of stations
from which you need to collect data more frequently.
The default size is 64 words.
Normal poll group size The number of stations that the master polls before it polls a
station in the priority poll list.
Active station file A binary file that stores the station addresses of all active
stations on the link.
The default size is 18 words.
Both the normal poll list and the priority poll list can have
active and inactive stations. A station becomes inactive
when it does not respond to a master’s request for data.