3-5
Brooks
®
Digital MFC's & MFM's
Section 3 Operation
Installation and Operation Manual
X-TMF-SLA5800-Series-RevB-MFC-eng
Part Number: 541B187AAG
January, 2017
Zeroing the MFC
It may be desirable to re-zero the flow sensor if it is operated at its
temperature extremes or if it is positioned in an attitude other than that
specified on the customer order.
To zero the device’s sensor:
1. Allow the device to be powered on for 45 minutes so that it achieves its
operating temperature.
2. Close the downstream shutoff valve.
The device should be full of process gas with no pressure
differential.
3. Wait at least 30 seconds for the flow signal to drop to zero.
4. Using the device’s Zero pushbutton, zero the device:
-
press the pushbutton until the device’s Status LED flashes red, then
release the pushbutton. A successful zeroing
operation is indicated by the Status LED being a steady green.
The zeroing operation can take up to 10 seconds to complete.
Note: Before zeroing the instrument, zero pressure differential MUST be established
across the device. If there is pressure across the instrument during the zero process,
any detected flow through the sensor will be misinterpreted as the zero flow reading.
This will result in calibration inaccuracy during normal operation.
Once zero differential pressure is established and verified, press the recessed,
momentary push-button (zero button) located on the side of the device
(See Figure 3-2) to start the zero function.
3-5
Communications Features
3-5-1
RS485 Communications Features (Analog versions only)
Digital communication, designed to emulate the Brooks S-series
"S-protocol" or pseudo-HART communications is available on the Brooks
Digital Series via RS485. This form of multi-drop capable communication
provides access to many of the Brooks Digital Series functions for "control
and monitor" operations, including:
•
Accurate setpoint adjustment flow output measurement
(including units of measure selection)
•
Valve Override (controller only)
•
Flow Totalizer
•
Alarm status and settings
•
Soft Start Control (controller only)
RS485 equipped units support the following baud rates. Please specify the
desired baud rate when ordering (default is 19200 baud). Alternately, baud
rate may be changed using the Brooks Expert Support Tool (BEST).
Baud Rates: 1200, 2400, 4800, 9600,
19200
and 38400
Reference the Brooks document "Supplemental Manual for RS485
Communications for Brooks
®
MFCs/MFMs, for SLA5800/SLAMf Revsion B
Series" (X-DPT-RS485-SLA5800-SLAMf-Series-RevB-MFC-eng) for more
details regarding the capabilities of this communication interface.
