TCP/IP Connection

Overview

One method of connecting to a device and communicating with it is via a TCP/IP connection. Often Port servers are used closer to the devices in the field to convert the TCP/IP communications to Serial for connectivity over Ethernet networks. 

TCP/IP ports use socket connections to communicate with field devices. The socket connections are opened when polling is required and if configured can close when it is complete. 

Logical ports are defined within ACM to represent a communication method used to connect to a device. Each logical port (Port) has a name that is used to reference it. Whenever a port is used, all of the settings defined by that port are used for communications. Multiple devices and/or multiple device types in ACM can use a single port for communications.

TCP/IP ports release connections between poll intervals.

Configuration

Once a port has been added to the ACM server, the port must be configured by editing the created object. Configuration may be accomplished using the default Form view. 

Port Tab

Connection Type

The type of connection to establish with the remote address.

• TCP (default)
• UDP
  • Select UDP Receive Port Default = not selected.  Select to use a specific UDP port instead of allowing Windows to select the port.
  • UDP Receive Port Default = 0. The local port to use for receiving UDP communications.

Selected Host

Select Host 1 or Host 2 to configure.

Auto Switch Hosts

Automatically switch to the other host upon failure.

Host Address 1, Port. 

The host name and IP address and port of Host 1.

Host Address 2, Port. 

The host name and IP address and port of Host 2.

Port Control

The method used to determine exclusive control of the connection.

• Maintain Control (Default) - When selected, this option maintains control of the TCP/IP connection and keeps it connected to the target IP address whether devices are actively polling or just waiting for their scheduled poll to come due. Use this option when devices poll frequently, or there are enough devices on the connection port to keep it busy. This option may also be required if ACM must detect unsolicited messages arriving from a field device.
• Release When Done - When selected, this option closes the TCP/IP connection after each device is done polling. The sequence is to 1) Open the TCP/IP connection when a device is ready to poll; 2) Poll for the data needed by the device; 3) Close the TCP/IP connection (after the 'Port Release Delay' period has elapsed). Use this option when polling on the port is infrequent, or if the target TCP/IP connection has to be shared with other applications.

Port Release Delay

The length of time in milliseconds to keep control of the port after communication is done.  Used in conjunction with Port Control = Release When Done.

Lost Connection Timeout

The maximum length of time in seconds to allow to pass with no incoming data before closing the port and reestablishing the connection.

Enable Dialup Modem

Use a modem when communication through this port.

Port Options

Lazy Connection. Select to prevent ACM from attempting to re-establish the connection before the next poll.

Commands

See Object Commands for how to locate and execute a command.