FAQ-Total Pressure Measurement


Question: Why does the display shows a much lower pressure than usual?
Answer: If the displayed pressure is much lower than expected, contamination could be the cause. These contaminants can also lead to a fluctuating behavior of the indicated pressure. In this case a degas needs to be performed (see manual: page 31).

Question: The display of the MVC3 indicates the error "Err p". What does that mean?
Answer: In most cases, there is no error, but the actual pressure in the chamber is greater than 1e-2 mbar.

Question: What is the meaning of the displayed error "Fil br"?
Answer: First possibility: A filament broke and must be replaced. Verification: see "Confirming a filament breakage".
Second possibility: The anode is dirty and the sensor needs to be returned.

Question: How can I confirm a filament breakage?
Answer: The pins B1, B2 and C must be connected on the atmosphere side: R < 1 ohm. This can be verified with the use of a multimeter.

Question: The error "Err Ba" is displayed on the MVC3. What shall I do?
Answer: A possible cause for this error message is the electrical contact of one of the electrodes to ground or to each other. If this is the case, the sensor head is required to be returned to us. Note: The pins B1-C, B2-C, DD are connected (R <1 ohm). If a short circuit is not the cause, a degas often helps to fix the error.

Pin assignment

I have problems with pressure measurement at low UHV or XHV?


One cause for a wrong displayed pressure  can be the presence of magnetic leakages, for example close to an ion getter pump.

Question: Why I cannot establish a connection between the MVC3 and the PC?

Therere are multiple reasons for that problem. It should be checked whether the same baud rate and the same protocol (RS232 or RS485) is set on both sides (PC and MVC3). You can not use a null modem cable. To get the right RS485-Adress of the MVC3, connect it to the PC temporarily over RS232:

  • Baud rate as set in MVC3
  • 8 Data bits
  • 1 Stop bit
  • No parity
  • No protocol

By sending RSA the RS485-Adress is sent in the form 0xXX  with XX as RS485-adress. After getting this adress the device must be re-set to RS485. To do that, press long on [CONFIG], then choose "ParA Gen" via pressing [►] and press [CONFIG] until you see "rS". There, you can set the protocol to RS485 by pressing [►]. After that procedure the MVC3 has to be switched off and turned back on again. Now, a RS485 communication can be established as follows: XX<Command>.
Attention: No comma between RS485-adress and command.


Question: Why does the function of Adjust VAC has no effect?
Answer: For this purpose you must proceed in the menu structure as follows:
Settings => Digital Sensor => Emission Off => Adjust VAC => Emission Auto => Both Filaments

Question: The firmware update has been not completed. What should I do?
Answer: Please restart the update process from the beginning as described in the manual***. If the update fails again, please contact your sales representative.
*** see manual chapter 5.6


Question: The ATMION® shows an incorrect pressure value or the pressure indicator is shown fluctuating. What could be the reason?
Answer: If the displayed pressure is significantly lower than expected, contamination can be a reason. This can also lead to a fluctuating behavior of the displayed pressure. In such cases, a Degas* needs to be performed. Another reason for fluctuating pressure values may be a too high temperature at the control electronics. It should not exceed 40 ° C.
* For Y-Cable ATMION® see manual page 13
  For MVC-3 see manual page 31
  For ATMIGRAF® see manual page 17
Question: A light is flashing yellow and green in turns. Is the sensor switching back and forth between two measurement modes?
Answer: Yes, that is correct. In this case, the Pirani needs to be adjusted. A pressure calibration** needs to be performed at atmosphere pressure and at p < 1e-3 mbar.
Important: This calibration only works in the Pirani mode. In auto mode, no adjustment will be made.
** For Y-Cable ATMION® see manual page 13
    For MVC-3 see manual page 44
    For ATMIGRAF® see manual page 15
Question: A red flashing light appears on the ATMION®. Is this a Pirani fault?
Answer: Yes. In this case the measurement head needs to be replaced.

Question: An incorrect pressure is displayed in the Pirani mode. Has the calibration changed?
Answer: Yes, it is recommended that an atmospheric and vacuum pressure calibration** is performed after each ventilation cycle.
After disassembly and reassembly of an ATMION® it is important to note that the Pirani measurement method is slightly dependent on position and, accordingly, a new calibration must be performed.

** For Y-Cable ATMION® see manual page 13
    For MVC-3 see manual page 44
    For ATMIGRAF® see manual page 15

Question: When evacuating the indicated pressure remains at approximately 1e-3 mbar, however, my chamber pressure is considerably lower. Is my device broken?
Answer: No. The reason is often a lack of a vacuum calibration.

Question: How can I check if the sensor is fully functional?
Answer: Errors in the sensor head can be avoided by checking the pins on the atmosphere side. Simultaneously, it is verified whether or not everything is properly connected. The filament connectors B1, B2 and C (R < 1 Ohm) have to be connected as well as both Pirani wire connectors D-Pin (R ca. 2 k Ohm) and both anode connectors F-Pin (R < 1 Ohm).
Among each other the pins should not be connected. Also, the pins should not have a short circuit to ground.

Pin Configuration

Here we answer frequently asked questions. If you have any questions on our products, you can also contact your Sales Representatives.

The firmware update has been not completed. What should I do?