MKS P9B, Instruction Manual, Page: 53 / 112

Digital Interface Input and Output Options Chapter Four: Analog and Digital Interface
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Unrecoverable Fault Condition
A hardware problem with the EEPROM, or a memory problem with the RAM are major unrecoverable faults.
This fault condition sets its exception status bit, and the Module Status LED illuminates solid red, complying
with Volume I of the DeviceNet Specification.
Note
A major unrecoverable fault prevents operation because the device cannot communicate on the
network. Contact MKS Instruments, Inc. for assistance.
Power Up
At power-up, the flow device performs checks on its communications link and internal diagnostic checks of
the EEPROM and RAM. The results of these checks are indicated by the color (green or red) and condition
(solid or flashing) of the status LEDs on top of the instrument. The following LED sequence occurs when the
MFC is powered up (times are approximate):
1. The Module Status LED flashes first GREEN for ¼ second, then RED for ¼ second, then turns OFF.
2. The Network Status LED flashes first GREEN for ¼ second, then RED for ¼ second, then turns OFF.
3. The Module Status LED flashes from GREEN to RED for five seconds while the device is initializing.
The Network Status LED remains OFF.
4. The Module Status LED illuminates solid GREEN when initialization is completed.
5. When the device establishes communication with other devices on the network, the Network Status LED
illuminates GREEN.
Note
If the power up LED sequence does not function properly, contact MKS for assistance.
See Table 7: Network Status LED Indicators for more information on the operation of the
Network Status LED and the Module Status LED.
Warm-Up and Zero the MFC
Warm Up Time
After installation and power connection, allow the MKS MFC to warm up for a minimum of 30 minutes.
This is to account for both warm-up of the device electronics as well as for the device to reach ambient
temperature conditions.
Zeroing the Device
Although MKS flow devices are zeroed at the factory prior to shipment, it is normal to check the zero and re-
zero them, if needed, when they are first installed on the tool.
A mass flow meter or mass flow device will provide a zero output signal under no flow gas conditions.
Zero offset from improper zeroing procedures can contribute to flow measurement inaccuracy. This is more
apparent at the lower end of the device flow range.
In order to complete a true zeroing of the device, ensure the following conditions are satisfied prior to
beginning the procedure.

Device is installed in the orientation intended for final use (i.e. horizontal base down, vertical flow up,
etc.).