10 Control
Alicat ASCII Serial Communication
Alicat ASCII Serial Terminal is a pre-congured program for serial communications via the
instrument’s 6-pin connector. Download Serial Terminal for free at alicat.com/drivers.
Serial commands are not case-sensitive. In the descriptions below, however, the commands
are shown in uppercase while command variables are shown in lowercase to help dierentiate
them.
All commands must be prexed with the unit_id, the unique identier for the instrument.
Instruments will also accept commands beginning with *, which is used as a broadcast value.
The unit_id must be the rst character after a carriage return ().
Unless otherwise noted, there must be a space between the command and any arguments.
All commands must end with a carriage return (), decimal value 13, hex value 0x0D).
After a carriage return is received, the instrument does not start acting upon or responding
to a command until the serial idle timeout is reached (the time needed to transmit 3.5 bytes).
All responses are a single line terminated with a carriage return. If a new command is started
before the carriage return of the response of the previously issued command has been
received, the behavior of the instrument is undened.
Establishing Communication
Connect the instrument to a computer through a COM port or virtual COM port, noting the
COM port number. Up to 26 instruments can be connected to a single COM port.
The following are the default connection settings:
• Baud: 38400 (see page 17)
• Data bits: 8
• Parity: none
• Stop bits: 1
• Unit ID: A (see page 16)
Data Frame Format
Data can be read from the instrument as the complete data frame, or you can choose specic
data to report. The complete data frame is:
A +24.57 +100.0 +0021513.0 +100.0 +55.13 N2 [ T O V ][ M O V ][O V R][ H L D][ V T M ]
unit _ idtemp. ow total setpointvalve _ drivegasErrorConditions
where:
unit _ id: The text ID of the instrument.
temperature: The current temperature of the instrument, in °C.
ow: The current ow reading of the instrument, in the congured units.
Total: The total volume (read from the totalizer)
setpoint: The current setpoint value, in the same units as ow.
valve _ d rive: The valve drive will be reported in percent of full drive.
gas: The currently selected gas.
If present, the following error condition abbreviations indicate:
TOV Temperature overrange.
MOV Mass ow overrange.
OVR Totalizer overrange.
HLD Valve hold is in use (see page 13).
VTM Valve thermal management is active (see note below).
