Flow Zero Adjustment Chapter Seven: Maintenance
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Via the protocol Zero Service.
For DeviceNet – Refer to “MKS G-Series MFC, Devicenet Supplement” 1046412-001.
For Profibus – Refer to “MKS G-Series MFC Profibus Supplement”, 1046413-001
For RS485 – Refer to “MKS G-Series MFC, RS485 Supplement”, 1046411-001.
Flow Zero Adjustment Procedure
1) Assure that the MFC is setup in the exact process conditions:
a) Verify that the MFC is installed in the final equipment and orientation (base up, base down, vertical
flow up, etc.)
b) Verify that the MFC is powered at operating temperature for at least 30 minutes.
c) If the MFC will be subjected to elevated ambient temperature conditions, verify that these
temperatures have been achieved and stable for at least 30 minutes before continuing.
2) Verify that the pressure drop across the MFC is reduced to zero and zero the device. Depending on the
gas panel configuration, this may be done by one of the following procedures.
a) System has upstream and downstream positive shut off valves
i) Close the upstream valve.
ii) Close the downstream valve.
iii) Open the MFC’s control valve.
iv) Allow pressure across MFC to equilibrate as flow output approaches zero and stabilizes.
v) Close the MFC’s control valve.
vi) Wait one minute and adjust the zero using one of the methods specified for the device I/O type.
b) For systems with downstream valve only - Zero the MFC at typical operating inlet pressure.
i) Close the downstream valve.
ii) Open the MFC’s control valve.
iii) Allow pressure to equilibrate across the MFC as flow output approaches zero and stabilizes.
iv) Close the MFC’s control valve.
v) Wait one minute and adjust zero using one of the methods specified for the device I/O type.
c) For systems with upstream valve only - MFC may be re-zeroed with downstream line under
vacuum or atmosphere.
i) Close the upstream valve.
ii)
Open the MFC’s control valve.
iii) The MFC may be evacuated to vacuum or exposed to atmosphere on downstream side. For either
case, the downstream pressure must be kept constant to insure there is no pressure drop across
MFC.
iv) Allow pressure to equilibrate across MFC as flow output approaches zero and stabilizes.
v) Close the MFC’s control valve.
vi) Wait one minute and adjust zero using one of the methods specified for the device I/O type.
DeviceNet Zeroing Commands
The MFC must be in the executing state then send the zero service with a target value of zero. The following
assumes explicit messaging only using the DeviceNet communication protocol.
Place the device in the Executing State through the S-Device Supervisor Object: Note the response Status:
Success
The following DeviceNet Command places the device in executing.
Service 0x06, Class 0x30, Instance 1
1. Verify you are in executing through the S-Device Supervisor Object: Note the response Data (hex): 04
means we are in executing. Attribute 0x0B The following DeviceNet Command is used to verify you are
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