LEYBOLD THERMOVAC TTR 101 N, Operating Manual, Page: 20 / 42

20 300544655_002_C1 - 11/2016 - © Leybold
Operations
5.1
Pressure output
The TTR 101N THERMOVAC transmitters can provide pressure measurement output as an analog voltage, RS232
digital value (P/N: 230366V02) or EtherCAT digital value (P/N: 230702V02). For details about the digital interface,
please refer to the Communication Protocol 300544663 (RS232) and 300544664 (EtherCAT).
The analog output is per default based on the MEMS Pirani and Piezo absolute combined reading and provides a
16 bit voltage output of 1.286 VDC/decade standard configuration. Refer to chapter 5.2 for details.
The Piezo absolute reading and the MEMS Pirani reading are combined into one smooth pressure reading with
superior measurement performance throughout the entire pressure range of more than 8 decades.
The measurement switching is gas dependent with the following pressure values:
Combined reading measurement
Gas setup MEMS Pirani
Reading
MEMS Pirani /Piezo
absolute integration
Piezo absolute
Reading
All gas settings <6.7 mbar 6.7-14.7 mbar >14.7 mbar
Resolution
The digital pressure output can provide three digit or four digit values. However, the resolution is limited in certain
parts of the measuring range.
1x10
-5
to 1x10
-4
mbar one digit resolution 1.000x10
-5
1x10 -4 to 1x10 -3 mbar two digit resolution 1.200x10 -4
1x10 -3 to 900 mbar three or four digit resolution 1.234x10 -3
Measuring noise
External sources can interfere with the sensor signal and cause noise on the signal. The low measuring range is
most sensitive to measuring noise due to low signal levels.
When designing external pressure control loops make sure that external equipment like pumping
system is not damaged if the transmitter output enters Sensor defect mode or in case of power
failure.
When designing pressure data collecting software and controlling loop make sure that the software
does not interpret a communication error as a valid pressure value.
Caution
Caution
!
!
!
!