5.3.4.1. Port

A system will not be called as HMI/SCADA if it is not communicating with any external device. Port is the first channel to determine in accessing the external devices. A Port can be a serial or parallel communication port, or an ethernet port, or any physical connectivity to the external devices, for instance a proprietary PCI device interface card.

 Setting

Name

Name of the communication port.

Description

Additional description.

Address

Physical port address.

This is usually a serial port address for devices connected via serial port, a parallel port address for devices connected via parallel port, or a TCP port address for devices connected on the local area network or wide area network.

For serial port address, enter COM followed by an integer from 1 onwards.

 

Example 5.10. Serial port address

COM2

For parallel port address, enter LPT followed by an integer from 1 onwards.

 

Example 5.11. Parallel port address

LPT1

For TCP address, enter IPv4 address, hostname, or IPv6 address if supported by the protocol and the device.

 

Example 5.12. TCP port address

For connecting to destination device with specific port number, specify its IP address and port number. This is applicable for most of the industrial protocol, like Modbus.

This example connects to a destination device with fixed IP address with port number.

192.168.1.10:502

For connecting to destination device without specific port number, specify its IP address. This is applicable to some of the protocol, like OPC.

This example connects to a destination device with its hostname.

MyOpcServer

Interval

Interval or delay in milliseconds between devices connected to the same physical port. Valid range of number is from 1 to 10000. Put -1 if do not want to use interval.

For serial and parallel ports, all devices will share the same communication channel, so there is only 1 connection opened with the port. If connecting to slow devices, it is useful to specify a delay to allow I/O manager to wait for its response before switching to another device. This is useful to avoid any multi drop configuration clashing in serial communication or handling network congestion.

For TCP port, each device will have at least 1 connection opened. You can specify the number of connections for each device connected to this port. Please refer Max Connection in Device for more details.