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Using the Watchport Sensor Interface
The Watchport line of USB attached sensor products present themselves to a user application by
way of a virtual serial port. This serial port is named as all standard serial ports in the form of
COMx where x is a number between 1 and 255. The number assignment can be configured using
the Edgeport configuration utility. (Refer to "The Edgeport Utility Program" on page 16.)
There are two basic types of sensing devices: the first type uses an ASCII command interface
and the second type uses an RS-232 modem signal interface. The serial port can be opened with
any serial parameters.
The first type of sensing devices uses ASCII commands. All ASCII commands sent to the sensing
device must be terminated with a carriage return character <CR>. Multiple commands may be
grouped together. For example, TCTF<CR> would cause Celsius temperature followed by
Fahrenheit temperature to be returned in the response.
The format of the response sent from the Watchport sensor to the application is an ASCII
printable character string terminated by a <CR>. For example, sending the command TF<CR>
generates a single response string such as +72.0000F<CR> and sending a grouped command
such as TCTF<CR> generates two responses such as
+22.2200C<CR> followed by
+72.0000F<CR>.
Other response strings generated by the Watchport sensor include Invalid Command<CR> or
Sensor Error<CR>.
The second type of sensing device uses the modem signals: DSR (Data Set Ready), DCD (Data
Carrier Detect), or CTS (Clear To Send) to inform the application of the status of the sensor.
The following section describes each sensor and its command or signal interface.
Additional information is available at www.ionetworks.com and Inside Out Networks' technical
support at 512-306-0600.
Watchport Installation Guide (90000406 Rev. D) – Page 9
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