Dh-485 configuration parameters, Devices that use the dh-485 network – Rockwell Automation 1766-Lxxxx MicroLogix 1400 Programmable Controllers User Manual User Manual
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Rockwell Automation Publication 1766-UM001H-EN-P - May 2014
Appendix E Connecting to Networks via RS-232/RS-485 Interface
• maximum network segment of 1,219 m (4,000 ft.)
The DH-485 protocol supports two classes of devices: initiators and responders.
All initiators on the network get a chance to initiate message transfers. To
determine which initiator has the right to transmit, a token passing algorithm is
used.
Control of message transfers on the DH-485 network is performed by rotating
the token along the nodes on the network. A node holding the token can send a
message onto the network. Each node is allowed a fixed number of transmissions
(based on the Token Hold Factor) each time it receives the token. After a node
sends a message, it passes the token to the next device.
The allowable range of node addresses is 1…31. There must be at least one
initiator on the network (such as a MicroLogix controller, or an SLC 5/02 or
later processor).
DH-485 Configuration Parameters
When MicroLogix communications are configured for DH-485, the following
parameters can be changed:
Software Considerations on page 191
for tips on setting the parameters listed
above.
Devices that use the DH-485 Network
In addition to the MicroLogix controllers, the devices shown in the following
table also support the DH-485 network
.
DF1 Full-Duplex Configuration Parameters
Parameter
Options
Baud Rate
9600, 19.2K
Node Address
1…31 decimal
Token Hold Factor
1…4
Devices that Support DH-45 Network
Catalog
Number
Description
Installation
Function
Publication
Bulletin 1761
Controllers
MicroLogix 1000 Series C or later
These controllers support DH-485 communications.
Bulletin 1762
MicroLogix 1200 Series A or later
These controllers support DH-485 communications.
Bulletin 1763
MicroLogix 1100 Series A or later
These controllers support DH-485 communications.
Bulletin 1764
MicroLogix 1500 Series A or later
These controllers support DH-485 communications.
Bulletin 1747
Processors
SLC 500
Processors
SLC Chassis
These processors support a variety of I/O requirements and functionality.