Publication 1766-RM001A-EN-P - October 2008
Communications Instructions
439
Remote Messages
The controller is also capable of remote or off-link messaging. Remote
messaging is the ability to exchange information with a device that is not
connected to the local network. This type of connection requires a device
on the local network to act as a bridge or gateway to the other network.
Remote Networks
DH-485 and DH+ Networks
The illustration below shows two networks, a DH-485 and a DH+
network. The SLC 5/04 processor at DH-485 node 17 is configured for
passthru operation. Devices that are capable of remote messaging and are
connected on either network can initiate read or write data exchanges
with devices on the other network, based on each device's capabilities. In
this example, node 12 on DH-485 is a MicroLogix 1400. The MicroLogix
1400 can respond to remote message requests from nodes 40 or 51 on the
DH+ network and it can initiate a message to any node on the DH+
network.
This functionality is also available on Ethernet by replacing the SLC 5/04
at DH-485 node 17 with an SLC 5/05 processor.
TIP
The MicroLogix 1000 can respond to remote message requests, but it
cannot initiate them.
TIP
The MicroLogix 1400 capabilities are the same as the MicroLogix 1200 or
MicroLogix 1500 in this example.
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