Installation guide

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3.9 Communications Parameters Screens
3.9.1 General
Below the Communication devices screens are the individual communications devices. This allows you to
configure a particular RS485 link, Ethernet link or GSM modem (for SMSs).
3.9.2 Communications device settings
Name and Description
These fields allow you to add information that allows you to quickly identify the communications device. They
do not affect the device operation. The name must be unique (if it is not the program will use the first com-
munications device with that name).
Comm. mode
There are a variety of different ‘Comm. Modes’ that are either Serial or Ethernet based. Ethernet based
modes require only the IP address and port number. Serial modes require settings for the serial port and se-
rial communications parameters.
• Modbus RTU – 232/422/485 - Communicates over a PC COM Port using Modbus RTU protocol.
The physical characteristics are determined by your computer hardware. Normally Modbus RTU de-
vices use RS485 links connected to some kind of virtual port (see above).
• Modbus RTU – UDP Raw – Connects directly to an Ethernet to serial converter using UDP protocol.
UDP protocol is a simple fast protocol that avoids some of the overheads of TCP.
• Modbus RTU – TCP Raw - Connects directly to an Ethernet to serial converter using TCP protocol.
TCP has higher overheads than UDP because it establishes a link between computer and converter;
it is still fast enough for most applications.
• Modbus TCP – The Ethernet TCP version of Modbus. The unofficial Port assigned for Modbus TCP
is 502.
• SMS Modem – Sends SMS messages via a PC COM port using AT commands. The physical char-
acteristics are determined by your computer hardware.
Timeouts
There are two timeout settings that are the same for Serial and Ethernet communications:
• Message time out (default = 1000 msec) – the time the software waits before resending a message.
• Time between messages (default = 50 msec) – a time delay that is inserted between messages.
Both values are set in milliseconds.