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Pressure Zero Adjustment Chapter Seven: Maintenance
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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
in executing.
Service 0xE, Class 0x30, Instance 1, Service Data (attribute) 0x0B
You should get response data of 0x04
2) Send the Zero Adjust Service using S-Analog Sensor Object Instance 1 (Flow)
The following DeviceNet Command Starts the Pressure zero.
Service 0x4B, Class 0x31, Instance 2, Service Data (Target Value) can be Empty Data or Data Type
based value, i.e. 2 byte for integer or 4 byte real value, if a value is used, it must be a target value equal
to zero.
3) The Flow zeroing procedure usually takes several seconds to perform. Recheck your flow to verify zero
has occurred. You can also perform an explicit GET(Service 0x0E) on Class 0x31, Instance 1, Attribute
0x1C, which is the Autozero Status. This attribute’s service data will equal “1” while zeroing is in
progress and equal “0” when the zeroing has completed. It is most important that the device is at a zero
flow, if a high flow is detected by the MFC, then zeroing will not occur.
Pressure Zero Adjustment
Recommended Interval
For the best accuracy and repeatability performance of the MFC, the zero pressure output of the device should
be periodically checked and reset, if necessary. All MFCs should be zeroed under actual installation
conditions prior to use. Offsets in the zero condition can contribute to flow measurement inaccuracy. This
may be especially noticeable at the lower end of the device range. At minimum, it is recommended that the
MFC be checked and zeroed, if necessary:

At the time of initial installation (or reinstallation).

Monthly, as part of a normal preventative maintenance procedure.
Methods to Adjust the MFC Pressure Zero
There are multiple methods to adjust the Pressure Zero of the P9B MFC. The methods available depend on
the I/O type, either analog or digital.
Analog I/O Devices

Via the Ethernet UI – Connect to the device using the Ethernet UI and enter the Setup Mode. Go to the
Configure Tab and zero using the “Zero Pressure” button on the screen. See Figure 26.