CTI 2572-A, Installation And Operation Manual

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CTI 2572-A Installation and Operation Guide V1.3 5
The 2572-A can support multiple concurrent client sessions. The server node shown in the
illustration could be another 2572-A module, a CTI 2572 module, a Siemens® 505-CP2572 module,
or a computer programmed to process the commands and send the appropriate responses.
Information describing the PLC logic required for client operation can be found in CHAPTER 5.
CAMP CLIENT COMMANDS.
The 2572-A can support multiple server sessions and multiple client sessions concurrently.
Therefore, networked PLCs can use the facilities of the 2572-A to participate in multi-session peer-to-
peer communications.
1.4. TCP/IP Overview
The CTI 2572-A module uses TCP/IP (Transmission Control Protocol/Internet Protocol) to transport
messages between the module and other nodes on the network. TCP/IP is a suite of protocols that
provide routing and delivery services for messages between application programs running on
different processors (called hosts in TCP/IP terminology). TCP/IP may be used on your local
Ethernet network, where it can co-exist with other protocols. In addition, it can be used on a Wide
Area Network (WAN), including the Internet.
Although TCP/IP provides network delivery services based on a global standard, using TCP/IP does
not guarantee that two workstations can effectively transfer data. To accomplish this, the nodes must
be using a common application protocol, such as CAMP. Most commonly used HMI applications
have driver software that supports the CTI 2572 CAMP message interface. In addition, OPC servers
are available from several sources, including CTI. For additional information about TCP/IP see
APPENDIX D. IP ADDRESS INFORMATION.
1.5. PLC Command Interface
Some 2572-A functions require that you use PLC logic to control the operation of the module. The
2572-A module provides a PLC logic interface for sending messages and processing responses that is
identical to the CTI 2572 module. The interface consists of two parts:
•
Command Blocks - Command Blocks are blocks of contiguous V memory words used to store
module commands and associated parameters. The exact content of the Command Block will
vary with the command being issued.
•
Module WX/WY Words - The 2572-A module logs in as a Special Function module and is
assigned two WX words and six WY words. PLC logic uses the WY words to select the
Command Block and to trigger the command execution. The status of the module and of
command execution can be monitored via the WX words.