18
Serial Communication
Serial Communication
Connecting your device to a computer allows you to log the data that it generates. The pressure controller communicates
digitally through its communications connector and cable using a real or virtual COM port on your computer. This section
of the manual shows you how to operate the pressure controller using ASCII commands.
Modbus RTU Communication
For details on Modbus commands, please visit
for the Modbus operating bulletin.
Establishing Communication
After connecting your pressure controller using a communications cable, you will need to establish serial communications
through a real or virtual COM port on your computer or programmable logic computer (PLC).
•
If the device is connected to a serial port, note its COM port number. This can be found in Windows® Device Manager.
•
If you have used a USB cable to connect your device to your computer, then in most cases it will recognize your USB
as a virtual COM port. If it does not, download the appropriate USB device driver at
and note the
COM port number as found in Windows® Device Manager.
The controller will be configured with the following settings:
• Baud:
19200 (by default; others can be used if the computer, its software, and the controller are all set to the same rate)
• Data bits:
8
• Parity:
none
• Stop bits:
1
• Flow control:
none
Alicat’s Serial Terminal Application
Alicat’s Serial Terminal is a preconfigured program for serial communications, functioning much like the older Windows®
HyperTerminal.
Download Serial Terminal for free at alicat.com/drivers. Once downloaded, simply run SerialTerminal.exe. Enter the COM
port number to which your device is connected and the baud rate of the pressure controller. The default baud rate is
19200, but this is adjustable by entering the
RS-232
Serial
menu on your pressure controller (
✓
Note:
In the following examples,
indicates an ASCII carriage return (decimal 13, hexadecimal D). For many devices, this
is the same as hitting the Enter key. Serial commands are not case-sensitive.
Polling Mode
Your controller is shipped in polling mode with a unit ID of A, unless requested otherwise. Each poll returns one line of
data every time you request it. To poll, simply enter its unit ID.
Poll the device:
[unit ID]
Example:
a
(polls unit A)
You can change the unit ID of a polling device by typing:
Change the unit ID:
[current unit ID]
@=
[desired unit ID]
Example:
a@=b
(changes unit A to unit B)
You can also do this via the device’s front panel menu (
). Valid IDs are letters A–Z, and up to 26 devices may
be connected at a time, as long as each unit ID is unique.
