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Publication 1761-UM006A-EN-P - February 2001
Connecting 1769-L20 CompactLogix Controllers on Ethernet 7-3
General Ethernet
Information
Each Ethernet device requires a unique IP address. If your Ethernet
network is isolated from the company-wide network, any valid IP
addresses may be used. If your Ethernet hub is connected to a larger
Ethernet network, contact your System Administrator for unique IP
addresses. For this example, the following IP addresses will be
assigned to the various Ethernet devices on our network:
The subnet mask for each Ethernet device is then, 255.255.0.0.
Rungs 0 and 1, shown in Figure 7.2, of the 1769-L20 controller’s ladder
program show an example of throttling two message (MSG)
instructions. In this case, sending a MSG to the SLC 5/05, and then
when it’s Done, initiating a MSG to the 1756-ENET/5550 controller and
so on. The two MSG Instructions will toggle, with only one
outstanding MSG at a time.
This is recommended for the 1769-L20 controller to keep the amount
of user memory needed for incoming and outgoing messages to a
minimum. Each message requires approximately 1.1K bytes of user
memory, allocated when the message is to be sent or received. If two
messages were enabled at the same time, 2.2K bytes of user memory
would need to be available.
Table 7.1 Example Network IP Addresses
IP Address Device
131.200.50.92 SLC 5/05 controller
131.200.50.93 1756-ENET
131.200.50.94 1761-NET-ENI #2 (1769-L20 controller)
131.200.50.95 1761-NET-ENI #1 (computer COMM port)
131.200.50.96 computer’s Ethernet card
IMPORTANT
The RS-232/DF1 interface between the L20 controller
and its ENI module, and between the computer
(RSLOGIX5000/RSLINX) and its ENI module, should
use 38400 baud. This will allow fast
upload/download of programs.
When using 38400 baud, the number of Stop Bits in
RSLINX and in the L20 controller must be set to 2.