HP MicroLogix 1761-NET-ENI manual Example Network IP Addresses Device, 131.200.50.95

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:

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

The subnet mask for each Ethernet device is then, 255.255.0.0.

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.

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.

Publication 1761-UM006A-EN-P - February 2001