Rockwell Automation 1761 MicroLogix 1000 Programmable Controllers - Manual (Page 340)

Preface MicroLogix 1000 Programmable Controllers User Manual
D–12
DH-485 Token Rotation
A node holding the token can send any valid packet onto the network. Each node is
allowed only one transmission (plus two retries) each time it receives the token.
After a node sends one message packet, it attempts to give the token to its successor
by sending a “token pass” packet to its successor.
If no network activity occurs, the initiator sends the token pass packet again. After
two retries (a total of three tries) the initiator will attempt to find a new successor.
The allowable range of the node address of an initiator is 0 to 31. The allowable
address range for all responders is 1 to 31. There must be at least one initiator on
the network.
DH-485 Configuration Parameters
When the system mode driver is DH-485 Master, the following parameters can be
changed:
Parameter Description Default
Baud Rate Toggles between the communication rate of 9600 and 19200. 19200
Node Address
This is the node address of the processor on the DH-485 network.
The valid range is 1–31.
1
Max Node
Address
This is the maximum node address of an active processor (fixed at
31). Set the node addresses of the devices on the network to low,
sequential numbers for best performance.
31
Token Hold
Factor Determines the number of transactions allowed to make each
DH-485 token rotation. (fixed at 1)
1