3.3.4   TCP/IP Com Port Properties

A TCP/IP type Com Port is a TCP/IP network card on the SCADA node. Picking TCP/IP means to use one of the network cards on the SCADA node to find the field devices.   A network connection that supports TCP/IP is required; Ethernet is the most common Network Interface Card (NIC) that supports TCP/IP.

TCP/IP is Transmission Control Protocol / Internet Protocol.  It is the protocol used by the Internet.  It is increasingly used in Automation.  Often an Ethernet LAN is dedicated to only the PLCs and other automation devices. Modbus Ethernet is an example of a TCP/IP protocol used in Automation.

There may be multiple Ethernet cards in your SCADA node in order to support communications to field devices and a second Ethernet card to other Client Workstations. Advantech WebAccess/SCADA will look over all Ethernet cards on the SCADA node to try to find the field device.

Figure 3-6Comport Properties - TCP/IP

Comport Number

This is a Virtual number used for reference.  It can be any number. The only consideration might be if you are also using a Serial Comport or other Device which requires the comport number to match that of the physical interface.

Description

User defined field for reference. This appears only in Project Manager.

Scan Time

This is the frequency of polling request for new data specified in Milliseconds.   The speed is largely determined by the PLC or field device and the nature of the network (how many other devices there are, how much data, the protocol, and baud rate). Refer to the Device Manufacturer's Manual for information on minimum scan times.

1000 Milliseconds means Advantech WebAccess/SCADA will try to update data once a second.  50 Millisecond scan times are not uncommon for connections to a single PLC.  50 Msec means Advantech WebAccess/SCADA will try to update data is 20 times per second.

The freshness of the data is largely determined by the protocol, some protocols are report by exception and include Deadbands that must be exceeded before a value is updated.

Auto Recover Time

Time to wait before attempting to re-establish communications with a BAD device or port.

Backup Port

This enables a redundant communications path to the Device. If communications can not be established through this Comport, Advantech WebAccess/SCADA will try a second Comport, specified as the Backup Port.  You must configure the backup Port number in Advantech WebAccess/SCADA, but without any devices on it.  Usually the device must have two comports also. Not all Device Types support a backup Port.

The Backup Port is usually configured as the same type.  However, some Device Types allow the backup port to be another physical type; for example, Modicon Device can use a TCP/IP (network) port with a Serial backup port.

See the specific Advantech WebAccess/SCADA Driver Manual for your device.