Specifications

37
SLC 500 Programmable Controllers and I/O Modules
Data Highway Plus
The Data Highway Plus (DH+) network is a local-area network designed to support remote
programming and data acquisition for factory-floor applications. You can also use DH+
communication modules to implement a peer-to-peer network.
You can use a DH+ network for data transfer to other PLC-5 controllers or high-level computers
and as a link for programming multiple PLC-5 controllers. A PLC-5 programmable controller can
communicate over a DH+ network with other controllers and with a workstation.
The DH+ network supports daisy chain and trunkline-dropline configurations. The number of
supported devices on a DH+ link and the length of the cable depends on the communication rate.
Data Highway Plus connectivity for the SLC 500 is provided by the SLC 5/04 processor;
see page 9 for more details.
DH-485 Network
The DH-485 communication network allows devices on the plant floor to share information. Via the network,
application programs can:
• Monitor process and device parameters and status, including fault and alarm detection
• Perform data acquisition
• Perform supervisory control functions
• Upload/download PLC programs over the network
The DH-485 network offers:
• Interconnection of up to 32 nodes
• Multi-master capability
• Slave devices
• Token-passing access control
• The ability to add or remove nodes without disruption of the network
1747-KE DH-485/RS-232C Interface Module
The DH-485/RS-232C Interface Module provides a bridge between the DH-485 communication network and RS-232 using Allen-
Bradley’s DF1 communication protocol. When used in a SLC 500 chassis with a modem, you can:
• remotely program and troubleshoot any single SLC 500 processor
• remotely communicate to a DH-485 network of SLC 500 processors
• remotely collect data directly from the data table of any SLC 500 processor
• use the SLC 500 as a remote terminal unit