# BASEstartm Open DAS
for Modicon®
on Tru64tm UNIX®
Installation and User's Guide

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## 2.3.2 Configuring Ports

You can physically connect a device to a Local Area Transport (LAT) port. To use a LAT port with the DAS, you must define the LAT port on the Tru64 UNIX system using the LAT control program.

For example, to define port_2 on the LAT node srvr4 as /dev/tty06, perform the following steps:

1. Log in as superuser.
2. Use latcp to define the port:

       # /usr/sbin/latcp -A -p tty06 -H SRVR4 -R PORT_2 -Q

Use the /usr/sbin/latsetup script to create the desired LAT ports and to create the entries in the /etc/inittab file. Do not create entries in the /etc/inittab for LAT ports that you want to use in communicating with the programmable controllers. Entries in /etc/inittab are only for interactive LAT ports.

Make sure that the protection on the device allows it to be accessed by the DAS software.

NOTE: Currently the LAT software on Tru64 UNIX does not recognize port disconnects properly and will not reconnect if the port is logged off. The LAT software also does not return an error if the LAT port has not been configured properly. For these reasons, care must be exercised when using LAT ports in a production environment.

For the DAS for Modicon programmable controllers to send and receive data correctly, you must set and define LAT port characteristics to match the line parameters defined in ODS for the corresponding port. The following example shows the characteristics set at the LAT prompt:

    Local> DEF PORT n SPEED 9600
    Local> DEF PORT n AUTOBAUD DISABLED
    Local> DEF PORT n AUTOCONNECT DISABLED
    Local> DEF PORT n FLOW DISABLED
    Local> DEF PORT n PREFERRED NONE
    Local> DEF PORT n ACCESS REMOTE
    Local> DEF PORT n CHAR 8
    Local> DEF PORT n PARITY EVEN

## 2.3.3 Configuring TELNET Access

You can physically connect a programmable controller to a terminal server using the TELNET protocol. Using the TELNET protocol allows the use of non-proprietary protocols to access terminal servers to perform device communications.

The terminal server being used must support the BINARY transfer option (RFC 856). The DAS negotiates binary transfer as part of establishing a connection with the port. If the terminal server will not allow binary transfer, the negotiation fails and a connection is not established.

NOTE: Using TELNET communications is slower than either LAT or a directly connected device. Ensure that your throughput requirements will be satisfied before deciding to implement TELNET communications.

For the DAS for Modicon programmable controllers to send and receive data correctly using TELNET, you must set up a port on the terminal server to receive a connect from the DAS. The following example shows setting up a port using a DECserver 700.

    Local> DEF TELNET LISTENER y PORT n
    Local> DEF TELNET LISTENER y CONNECTIONS ENABLED

The following example shows setting up the server for TELNET access. A gateway needs to be configured only if the terminal server is on a different subnet than the host. In general, the terminal server should be on the same subnet as the host in order to reduce communications delays.

    Local> DEF INTERNET ADDRESS xx.xx.xx.xx
    Local> DEF INTERNET MASK xx.xx.xx.xx
    Local> DEF INTERNET GATEWAY xx.xx.xx.xx

## 2.3.4 Setting Up Plant-Floor Equipment

To set up your plant-floor equipment, refer to the Modicon documentation for your specific device.

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