11
Control
proportionally changing the position of the valve.
Use the setpoint command (
unit_id
S
new_setpoint_value
) with the desired value in the
current engineering units. The data frame returns the new setpoint value when it has
been accepted as a valid setpoint.
To send the desired setpoint value as a floating point number in the engineering units
selected:
New setpoint:
unit_id
S
floating_point_number_setpoint
Example:
aS15.44
(setpoint of +15.44 SLPM)
Use the power-up setpoint command (
unit_id
SPUE
setpoint_value
) to create a new power-up
setpoint. Use a value of 0 as the setpoint_value to disable the power-up setpoint.
Additional setpoint options are described in the Serial Primer manual (
alicat.com/manuals
).
Totalizer
The controllers/meter totalizer can measure the total flow that has passed through the
device since it was powered on or since it was last reset. Totalizer counts are reset if power
to the device is lost.
To read the totalizer, poll the device (
unit_id
) using its current unit ID. For information on
reading the data line, see the Data Format on
).
To reset the totalizer, use the reset totalizer command (
unit_id
T).
Additional Totalizer functions and options are available in the Serial Primer manual
(
alicat.com/manuals
).
Batch Dispensing
For controllers, batch dispensing flows a set volume of gas, after which the valve closes
and the flow stops. You can repeat batches. To utilize batching, at least one totalizer
must be enabled. Batch functions and options are described in the Serial Primer manual
(
alicat.com/manuals
).
Changing the Gas
Factory OEM devices are calibrated to measure any of a selection of 30 gases. The gas
list is customizable and varies between devices. To find which gases are available on the
device, use the ASCII query gas list command (
unit_id
??G*
). The query gas list command
also lists their gas number.
To reconfigure your flow controller to flow a different gas, look up its gas number
(
). Here are the commands:
Choose a gas:
unit_id
G
gas_number
Example:
aG8
(reconfigures to flow nitrogen)
Control Loop
The controller can control the flow rate or the pressure in your process. Selectable control
loop variables include mass flow, volumetric flow, absolute pressure, and valve drive.
The loop can also be tuned to improve performance in some applications. Control loop
functions and options are described in the Serial Primer manual (
alicat.com/manuals
).
