LEYBOLD COMBIVAC CM 31 User manual

COMBIVAC CM 31
Cat. No.
157 89, 896 89, 897 89
Operating Instructions
Vacuum Pumps Instrumentation Fittings and Valves LEYBOLD VACUUM
GA 09.504 / 5.02

LEYBOLD-Service
If an appliance is returned to LEYBOLD, indicate
whether the appliance is free of substances damaging to
health or whether it is contaminated. If it is contaminated
also indicate the nature of hazard. LEYBOLD must
return any appliance without a declaration of contamina-
tion to the sender’s address.
General Note
The right of alterations in the design and the technical
data is reserved.The illustrations are not binding.
Contents Page
1 Description . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1.1 Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2 Technical data . . . . . . . . . . . . . . . . . . . . . . . 4
1.2.1 General data . . . . . . . . . . . . . . . . . . . . . . . . 4
1.2.2 TM measurement channels . . . . . . . . . . . . . 4
1.2.3 PM measurement channel . . . . . . . . . . . . . . 5
1.2.4 Relay outputs . . . . . . . . . . . . . . . . . . . . . . . . 5
1.2.5 Chart recorder outputs . . . . . . . . . . . . . . . . . 5
1.2.6 AC power requirements . . . . . . . . . . . . . . . 5
1.2.7 High voltage control input
(only for PENNINGVAC) . . . . . . . . . . . . . . . . 5
1.2.8 Mechanical data . . . . . . . . . . . . . . . . . . . . . 6
1.2.9 Ambient conditions . . . . . . . . . . . . . . . . . . . 6
1.2.10 RS 232 C interface
1.3 Technical description . . . . . . . . . . . . . . . . . . 6
1.3.1 COMBIVAC CM 31 . . . . . . . . . . . . . . . . . . . 6
1.3.2 THERMOVAC method of measurement
(Pirani) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
1.3.3 PENNINGVAC method of measurement
(cold cathode) . . . . . . . . . . . . . . . . . . . . . . . 6
1.3.4 RS 232 C interface . . . . . . . . . . . . . . . . . . . 7
1.4 Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . 7
1.4.1 Supplied equipment . . . . . . . . . . . . . . . . . . . 7
1.4.2 Accessories . . . . . . . . . . . . . . . . . . . . . . . . 7
2 Operation . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.1 Start-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.2 Electrical connection . . . . . . . . . . . . . . . . . . 8
2.2.1 Changing the line voltage setting and
exchanging the fuses . . . . . . . . . . . . . . . . . . 9
2.3 Controls and their functions . . . . . . . . . . . . . 9
2.3.1 Bar graph display . . . . . . . . . . . . . . . . . . . . . 9
2.3.2 Digital display . . . . . . . . . . . . . . . . . . . . . . 10
2.3.3 Measurement units . . . . . . . . . . . . . . . . . . 10
2.3.4 Status display area . . . . . . . . . . . . . . . . . . 10
Page
2.3.5 Keys TM 1, TM 2 and PM . . . . . . . . . . . . . . 11
2.3.6 Key HV . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
2.3.7 Key Decrement . . . . . . . . . . . . . . . . . . . . . 12
2.3.8 Key Increment . . . . . . . . . . . . . . . . . . . . . . 12
2.3.9 Key PARA . . . . . . . . . . . . . . . . . . . . . . . . . 12
2.3.9.1 Checking and setting up of the
equipment parameters . . . . . . . . . . . . . . . . 12
2.3.9.2 Locking of parameter settings . . . . . . . . . . 15
2.4 Supply and socket connections
on the rear . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.4.1 AC power supply . . . . . . . . . . . . . . . . . . . . 16
2.4.2 Connection of the THERMOVAC gauge . . . 16
2.4.3 Connection of the PENNINGVAC gauge . . . 16
2.4.4 Screw terminal outputs for the
THERMOVAC channels . . . . . . . . . . . . . . . 16
2.4.5 Screw terminal outputs for the
PENNINGVAC channel . . . . . . . . . . . . . . . 17
2.4.6 RS 232 C interface . . . . . . . . . . . . . . . . . . 17
2.5 Installing the instrument . . . . . . . . . . . . . . . 18
2.5.1 Installation . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.5.2 Rack installation . . . . . . . . . . . . . . . . . . . . . 18
2.5.3 Panel installation . . . . . . . . . . . . . . . . . . . . 18
2.5.4 Using the CM 31 as a table-top instrument . 18
2.6 Checking the equipment functions . . . . . . . 18
2.6.1 The THERMOVAC channels . . . . . . . . . . . 18
2.6.2 The PENNINGVAC channel . . . . . . . . . . . . 19
2.7 Alignment of the THERMOVAC
gauge heads . . . . . . . . . . . . . . . . . . . . . . . 19
2.8 Switching off . . . . . . . . . . . . . . . . . . . . . . . 19
2.9 Status messages . . . . . . . . . . . . . . . . . . . . 20
2.10 Chart recorder output tables . . . . . . . . . . . . 21
2.10.1 Chart recorder output tables for
TM measurement channels . . . . . . . . . . . . 21
2.10.2 Chart recorder output tables for
PM measurement channel . . . . . . . . . . . . . 23
2

Page
3 RS 232 C interface . . . . . . . . . . . . . . . . . . 25
3.1 Description . . . . . . . . . . . . . . . . . . . . . . . . 25
3.2 Interface parameters . . . . . . . . . . . . . . . . . 25
3.2.1 Baud rate . . . . . . . . . . . . . . . . . . . . . . . . . . 25
3.2.2 Data format . . . . . . . . . . . . . . . . . . . . . . . . 25
3.2.3 End and acknowledgement character
for remote operation . . . . . . . . . . . . . . . . . . 25
3.2.4 Output rate and end character for
printer output . . . . . . . . . . . . . . . . . . . . . . . 25
3.3 Initial operation . . . . . . . . . . . . . . . . . . . . . 25
3.3.1 Remote control operation . . . . . . . . . . . . . . 25
3.3.1.1 Cable link . . . . . . . . . . . . . . . . . . . . . . . . . 25
3.3.1.2 Baud rate and data format . . . . . . . . . . . . . 26
3.3.1.3 End character . . . . . . . . . . . . . . . . . . . . . . 26
3.3.1.4 Acknowledgement character . . . . . . . . . . . 26
3.3.1.5 Reset character . . . . . . . . . . . . . . . . . . . . . 27
3.3.2 Printer operation . . . . . . . . . . . . . . . . . . . . 27
3.3.2.1 Output of measurement data
to a printer . . . . . . . . . . . . . . . . . . . . . . . . . 27
3.3.2.2 RS 232 C baud rate and data format
for printer output . . . . . . . . . . . . . . . . . . . . 27
3.3.2.3 Output rate for printer output . . . . . . . . . . . 27
3.3.2.4 End character . . . . . . . . . . . . . . . . . . . . . . 27
3.4 Data output and data formats . . . . . . . . . . . 27
3.4.1 Measurement data output . . . . . . . . . . . . . 27
34.1.1 Remote control operation . . . . . . . . . . . . . . 27
3.4.1.2 Printer output . . . . . . . . . . . . . . . . . . . . . . . 27
3.4.2 Parameter output and response time . . . . . 28
3.5 Interface commands and data input
for A-series instruments with
RS 232 C interface . . . . . . . . . . . . . . . . . . 28
3.5.1 Formation of measurement data
and readout commands . . . . . . . . . . . . . . . 28
3.5.2 Trigger adjustment commands . . . . . . . . . . 29
3.5.3 Operating parameters . . . . . . . . . . . . . . . . 29
Page
3.6 Output of error messages . . . . . . . . . . . . . 29
3.6.1 Interface errors (ERI) . . . . . . . . . . . . . . . . . 29
3.7 Program examples for setting
the parameters . . . . . . . . . . . . . . . . . . . . . 30
3.8 Examples for the cable link between
the interface and an IBM ®-PC . . . . . . . . . . 34
4 Maintenance . . . . . . . . . . . . . . . . . . . . . . . 35
4.1 Service at LEYBOLD’s . . . . . . . . . . . . . . . . 35
5 Brief operating instructions . . . . . . . . . . 36
3

1 Description
1.1 General
The COMBIVAC CM 31 is supplied ready for
use. However, we strongly recommend rea-
ding these Operating Instructions so that
optimum operating conditions can be set up
right from the start.
These Operating Instructions contain important informa-
tion on the functions, installation, start-up, operation and
troubleshooting of the CM 31.
Important remarks concerning operational safety and
protection are emphazised as follows.
Warning Indicates procedures that must be strict-
ly observed to prevent hazards to peo-
ple.
Caution Indicates procedures that must strictly
be observed to prevent damage to, or
destruction of, the CM 31 and to attain
specified performance levels.
Note
Indicates special technical requirements that the user
must comply with.
The references to diagrams, e.g.(2/5), consist of the Fig.
No. and the Item No. in that order.
Unpack the CM 31 immediately after delivery, even if it is
to be installed at a later date.
Examine the shipping container for any external dama-
ge. Completely remove the packaging materials.
Note
Retain the packaging materials in the event of com-
plaints about damage.
Check that the CM 31 is complete (see Section 1.4).
Carefully examine the CM 31 visually.
If any damage is discovered, report it immediately to the
forwarding agent and insurer. If the damaged part has to
be replaced, please contact Leybold.
1.1.1 Purpose
The COMBIVAC CM 31 is a universal vacuum gauge
which combines two principles of measurement - Pirani
(Thermovac) and cold cathode (Penningvac) - for the
measurement and control of vacuum pressures within
the entire range between 1·10-9 mbar/Torr and atmos-
pheric pressure.
One PENNINGVAC sensor (PR 32, PR 25, PR 35 or PR
36) and max. two THERMOVAC sensors (TR 201, TR
205, TR 206 or also TR 211 and TR 216) may be con-
nected.
The built-in RS 232 C interface permits computer con-
trolled operation as well as the exchange of measure-
ment data between the COMBIVAC CM 31 and a com-
puter.
Please refer to the technical data of this instrument to
determine whether or not this instrument suits your appli-
cation.
1.2 Technical data
1.2.1 General data
Measurement range 1·10-9 mbar to 1·10+3 mbar
1·10-9 Torr to 760 Torr
THERMOVAC channels 2
PENNINGVAC channel 1
Measurement units mbar, Torr, Pa, Micron
(selectable)
Types of gas Air / N2, Ar (selectable)
Display
digital 7 segment LCD
analogue LCD bar graph
Resolution see tables 3 and 4 or tables 7 and 8 in
Section 2.10.1 or 2.10.2.
1.2.2 TM measurement channels
Measurement range 1·10-3 mbar to 1000 mbar
1·10-3 Torr to 760 Torr
Measurement uncertainty in the range
10-3 to 10-2 mbar / Torr: 20 % of the meas. value
10-2 to 10+2 mbar / Torr: 15 % of the meas. value
Sensors TR 201; DN 10 KF
TR 205; DN 16 CF and TR 206; DN 10 KF
TR 211; DN 16 KF and TR 216; DN 16 KF
Length of gauge head cable up to 100 m
Cable length alignment
automatically for TR 211 and TR 216
For TR 201, TR 205 and TR 206
Enter cable length in the
parameter mode (see Parameter-Page 9)
4

Trigger relays reaction time 30 ms approx.
for a pressure change exceeding
1 measurement decade
Trigger relays thresholds
2 per measurement channel; changeover contact
Modes level / interval
Ready indicator electrically 1 per measurement channel
floating n.o. contact
1 contact closed in ready mode
Error display FAIL optically, 1 per meas. channel
1.2.3 PM measurement channel
Measurement range1·10-9 mbar/Torr to 1·10-2 mbar/Torr
Measurement uncertainty in the range
1·10-8 mbar/Torr to 1·10-4 mbar/Torr
± 30 % of the meas. value
Sensors PR 25; DN 25 KF
PR 35; DN 40 KF
PR 36; DN 40 CF
PR 31 and 32 (limited measurement range)
Length of gauge head cable up to 100 m for the
pressure range 1·10-8 to 1·10-2 mbar / Torr
Trigger relays reaction time 40 ms approx.
for a pressure change exceeding
1 measurement decade
Triggers thresholds 2; changeover contact
Modes single / interval
Ready indicator electrically floating n.o. contact
1 contact closed in ready mode
Error display FAIL optically
1.2.4 Relay outputs
Two variable thresholds per channel with one relay
changeover contact each and one ready indicating cir-
cuit with n.o. contact.
Max. switching voltage 250 V AC / 60 V DC
Max. switching capacity 5 A (AC, resistive load)
0.7 A (DC)
Contact life 60,000 cycles
Setting range of the variable thresholds
PM channel 1·10-8 to 1·10-2 mbar
TM channel 5·10-3 to 500 mbar
3.7·10-3 to 370 Torr
Note
The relay outputs also have been designed to handle
signals for programmable controls.
1.2.5 Chart recorder outputs
Each measurement channel has its own chart recorder
output.
Voltage range 0 to 10 V (nominal)
(Limits - 0.6 V to + 10.6 V)
Load resistance Rext ≥2.5 kΩ
Output voltage in the
event of a fault 10.2 V to 10.6 V
Characteristic linear / logatithmic
PENNING
log. 1.43 V / decade
(0 V ;1·10-9 mbar)
linear: 0 - 10 V ;0 - 1·10-7 mbar
0 - 10 V ;0 - 1·10-6 mbar
0 - 10 V ;0 - 1·10-5 mbar
:
:
0 - 10 V ;0 - 1·10-2 mbar
THERMOVAC
log. 1.67 V / decade; (0 V ;1·10-3 mbar)
0-10 V ;5·10-4 - 1000 mbar (1,587 V / decade)
linear: 0 - 10 V ;0 - 1·10-2 mbar
0 - 10 V ;0 - 1·10-1 mbar
0 - 10 V ;0 - 1·100mbar
:
:
0 - 10 V ;0 - 1000 mbar
Reaction time 100 ms approx.
Resolution 2.5 mV (12 bit)
Deviation of the displayed value ± 2 %
1.2.6 AC power requirements
Line voltage (selectable) 100 V, 120 V
200 V, 230 V
+10 % / -15 %
Line frequency 50 to 60 Hz
Power consumption 35 VA
1.2.7 High voltage control input
(only for PENNINGVAC)
Input voltage 0 to 24 V DC
Max. input voltage range - 33 V to + 33 V
5

PC compatible logic level (LOW) < 7 V; 0 A
PC compatible logic level (HIGH)> 13 V; 7 mA (at 24 V)
Contact via relay approx. 24 V, supplied by the
instrument across a protection resistor
1.2.8 Mechanical data
Dimensions (WxHxD) in mm 106.5 x 128.5 x 285.5
Installation depth 375 mm
Weight 2.3 kg
1.2.9 Ambient conditions
Operating temperature 0 °C to 40 °C
Storage temperature -40 °C to 60 °C
Max. rel. humidity 80 % non-condensing
1.2.10 RS 232 C interface
Baud rate 2400, fixed
Data format ASCII character set
one start bit,
seven data bits + one space bit,
one stop bit
no parity
Signal level ± 8 V approx.
Operating modes for the single- and multi-channel
instruments of the A-series
- Talk-only operation automatic output of
measurement data every 10 s, in the
event of a fault output ofthe status message
instead of the measurement data
- Remote operation data acquisition,
status messages, parameter entry
(depending on the total pressure gauge used)
Connection plug Sub-D socket, 9-way
Active lines TxD (Transmit data) on pin 2
RxD (Receive data) on pin 3
GND signal ground on pin 5
Status signal DTR (Data terminal ready) on pin 6
RTS (Request to send) on pin 8
Shield pin 9
Max. cable length 20 m
1.3 Technical description
1.3.1 COMBIVAC CM 31
This combination instrument is equipped with three mea-
surement channels, two THERMOVAC channels and
one PENNINGVAC. Thus it is possible to measure and
control the vacuum in over 12 decades ranging between
1·10-9 mbar and atmospheric pressure. Six switching
thresholds, three logarithmic chart recorder outputs and
the self-monitoring facility permit integration of the COM-
BIVAC CM 31 into complex vacuum control arrange-
ments.The two THERMOVAC channels are immediately
active as soon as the line voltage is applied. The PEN-
NINGVAC channel may be switched on and off through
the second THERMOVAC channel (TM 2), externally or
manually via HV-key; see also Section 2.3.6.
All operating modes of the triggers and the gauges
aredisplayed and also signalled to the corresponding
outputs.
1.3.2 THERMOVAC method of
measurement (Pirani)
This method of measurement for the pressure range of
5·10-4 to 1000 mbar makes use of the thermal conduc-
tivity of the residual gas. In order to obtain response
times which are as short as possible, all THERMOVAC
instruments rely exclusively on the principle of the con-
trolled Pirani gauge.
The filament is part of a Wheatstone bridge. If the tem-
perature of the filament changes due to a change in the
pressure, the bridge then becomes unbalanced. A fast-
acting control circuit then adapts the heating power
applied to the filament, so that filament temperature
again reaches its nominal value and the bridge is reba-
lanced. The pressure readings obtained in this way
depend on the type of gas. Normally the readings of the
instruments are calibrated for nitrogen or air, with Argon
being selectable.
The mechanical design of the gauge heads is very rug-
ged and so, that dust cannot enter the electronics hou-
sing. Six types of sensors are available:
- TR 201 DN 10 KF /TR 211 DN 16 KF with tungsten fila-
ment for all standard applications
- TR 205 DN 16 CF which are bakeable and
- TR 206 DN 10 KF /TR 216 DN 16 KF with a nickel / pla-
tinum filament and of a corrosion protected design.
1.3.3 PENNINGVAC method of measure-
ment (cold cathode)
To measure the pressure a gas discharge is ignited wit-
hin the sensor by applying a high voltage. The resulting
ion current is outputed as a signal which is proportional
6

to the prevailing pressure. A new sensor design permits
safe and reliable measurement operation of this „inver-
ted Penning“ in the pressure range between 1·10-9 mbar
and 1·10-2 mbar.This sensor is available fitted with either
a KF or a CF flange. The special alloy used for the
magnet permits bakeing out of the sensor (with CF flan-
ge) up to 250 °C without having to remove the magnet.
The rugged electrodes may be simply taken out and ins-
erted again for cleaning or replacement.
1.3.4 RS 232 C interface
The interface will operate either in connection with a prin-
ter, remote control terminal or a computer.
The RS 232 C interface is suitable for transmitting data
over distances up to 20 m. By using converters such as
for example RS 422 or fibre optical links, much greater
distances can be covered. Moreover, with the aid of a
modem (modulator for transmission in the audio range
and demodulator for converting the signals back to digi-
tal) data may be transmitted down phone lines.
1.4 Equipment
1.4.1 Supplied equipment
Cat. No.
COMBIVAC CM 31
Europe 230 V; mbar 157 89
USA 120 V; Torr 896 89
Japan 100 V;Torr 897 89
Operating Instructions GA 09.504
Ref. No.
2 fuses T 0.315 A 520 25 310
2 fuses T 0.630 A 520 25 313
Power cord 2 m (depending on CM 31 version)
Europe 200 59 051
USA / Japan 200 27 550
Two 4-way screw terminal strips 200 60 806
One 5-way screw terminal strip 200 60 807
Three 8-way screw terminal strips 200 60 808
Four screws M 3 x 8 mm 200 80 029
Support stand for table use 200 60 900
Four adhesive feet 229 48 120
1.4.2 Accessories
Cat. No.
THERMOVAC gauge head TR 201, DN 10 KF 162 02
THERMOVAC gauge head TR 201, 1/8“ NPT 896 72
THERMOVAC gauge head TR 205, DN 16 CF 158 50
THERMOVAC gauge head TR 206, DN 10 KF 162 31
THERMOVAC gauge head TR 211, DN 16 KF 157 85
THERMOVAC gauge head TR 211, 1/8“ NPT 896 33
THERMOVAC gauge head TR 216, DN 16 KF 157 87
Replacement sensing cell TR 201, DN 10 KF 162 09
Replacement sensing cell TR 201, 1/8“ NPT 896 76
Replacement sensing cell TR 205, DN 16 CF 158 51
Replacement sensing cell TR 206, DN 10 KF 162 32
Replacement sensing cell TR 211, DN 16 KF 157 75
Replacement sensing cell TR 211, 1/8“ NPT 896 34
Replacement sensing cell TR 216, DN 16 KF 157 77
Gauge head cable 5 m for TR gauges 162 26
Gauge head cable 10 m for TR gauges 162 27
Gauge head cable 20 m for TR gauges 162 28
Extension cable 20 m for TR gauges 160 77
THERMOVAC gauge head simulator T 210 157 10
PENNINGVAC gauge head PR 25,DN 25 KF 157 54
PENNINGVAC gauge head PR 35,DN 40 KF 157 51
PENNINGVAC gauge head PR 36,DN 40 CF 157 53
Gauge head cable 5 m for PR gauges 162 88
Gauge head cable 10 m for PR gauges 162 89
Gauge head cable 20 m for PR gauges 157 56
Gauge head cables up to 100 m upon request
Test gauge T 35 (PENNINGVAC) 157 62
Installation frame 19“, 3 HU 161 00
Cover panel 1/4 19“, 3 HU 161 02
7

2 Operation
2.1 Start-up
Please refer to the technical data of this instrument to
determine whether or not this instrument suits your appli-
cation.
For safety reasons please check the following before
connecting the instrument to the AC power:
- The correct line voltage setting (on the rear)
see Fig. 1.
If it has to be changed, refer to Section 2.2.1
- The use of the correct line fuse.
For this refer to Section 2.2.1.
The COMBIVAC CM 31 is supplied ready for immediate
use.
Connect the gauge head via the corresponding gauge
head cable (refer also to Section 2.4).
Connect the AC power voltage to the CM 31 via the sup-
plied power cord. After applying power to the instrument
it runs a self test.When in progress, all display elements
come on briefly.
Depending on the operational status of your vacuum
system you will now get a corresponding pressure rea-
ding. Via keys TM 1, TM 2 or PM it is possible to select
the required gauge head.
Check or adjust the equipment parameters as appro-
priate according to Section 2.3.9.
Note
After having applied the mains voltage and after comple-
tion of the self test or after having exchanged a sensor
(TM channel) „TEST“ and „noSEn“ will be displayed
alternatingly for 1 to 5 seconds.While this is in progress
the instrument is trying to determine which THERMO-
VAC sensor is connected to the TM channel.
2.2 Electrical connection
Caution Before applying power to the instrument
for the first time, please carry out the fol-
lowing steps:
- Check and if required adapt the line
voltage setting to the local line voltage.
- Check and if required exchange the
built-in line fuse (see Section 2.2.1).
The line voltage of the CM 31 is set to the value which is
indicated upright on the AC power socket (legible) and
which points to the arrow (1/3) on the right side.
Integrated into the AC power socket is the line fuse and
the voltage selector for 4 different line voltage ranges.
The line voltage is applied to the instrument via the sup-
plied detachable power cord. An AC power socket (7/5)
is provided on the rear for connection of the power cord.
Warning Only 3-conductor power cords with
safety ground may be used. The instru-
ment may not be operated with an un-
connected safety ground conductor.
8
Key to fig. 1
1 AC power socket
2 Fuse insert
3 Arrow for indication of the line voltage setting
4 Slot for applying a screwdriver
Fig. 1 AC power socket (line voltage setting 230 V)

2.2.1 Changing the line voltage setting and
exchanging the fuses
To change the line voltage setting or
exchange a fuse the power cord must be
disconnected first.
To change the line voltage setting use a screwdriver to
remove the fuse holder (1/2) next to the socket (1/1).
Change the orientation of the fuse holder so that the
required voltage can be read upright pointing to the mark
(1/3). Insert the fuse holder (1/2), while at the same time
maintaining the orientation found.
Having changed the line voltage setting one of the follo-
wing fuses is required:
- 100 V: AC fuse T 0.63 A (Ø 5 x 20 mm)
- 120 V: AC fuse T 0.63 A (Ø 5 x 20 mm)
- 200 V: AC fuse T 0.315 A (Ø 5 x 20 mm)
- 230 V: AC fuse T 0.315 A (Ø 5 x 20 mm)
2.3 Controls and their
functions
An overview of the placement of the controls and the dis-
play elements is given in Fig. 2.
The instrument is operated via 7 keys.
Note
When pressing a key which has no function in that parti-
cular operating mode, symbol (2/9) comes on.
2.3.1 Bar graph display
The bar graph display (2/7) displays the measured value
in a analog manner with a log. scale.The arrows at both
ends of the bar graph display indicate an overrange or
underrange condition. Depending on the measurement
principle either the upper scale (exponents -3 to +3) or
the lower scale (exponents -8 to -2) will be in use.When
selecting the measurement unit Pa or Micron the scales
will remain unmarked.
9
Key to fig. 2
1KeyHV
2KeyPM
3 Key TM 2
4 Key TM 1
5 Status display area
6 Over- and underrange indicators
7 Bar graph display
8 Digital display
9 Indicator referring to the Operating
Instructions
10 Measurement units
11 Equipment fault
12 Key PARA
13 Increment parameter
14 Decrement parameter
Fig. 2 Arrangement of controls and displays

2.3.2 Digital display
The digital display (3/3) is used to digitally display the
pressure with respect to the selected measurement unit.
In case of Torr, Pa and mbar the readout is composed of
mantissa and exponent.
When selecting Micron the readout is composed only of
5 digits. Above 99000 Micron the readout automatically
changes over to Torr. 1.0·102Torr is indicated, and all
subsequent readings will be in Torr.
When the pressure drops below to 9.0·101Torr the dis-
play will then automatically return to the unit Micron.The
CM 31 will then display 90000 Micron and all subsequent
readings will be in Micron again. The lowest displayed
reading is 1 Micron.
2.3.3 Measurement units
Located to the right of the digital display is the display for
the pressure units (3/4). Only that unit will be indicated
which has previously been selected via parameter page
6.
When selecting the Micron pressure unit the reading will
change between Micron andTorr depending on the pres-
sure; (see Section 2.3.2).
2.3.4 Status display area
The status display area (3/1) for the measurement chan-
nels is located between the area of the keys and the
pressure display.
Trigger and equipment modes are indicated in the status
display area (3/1). These are related to the keys below
which are used to select the measurement channel. An
overview giving the arrangement of the trigger and
equipment status modes is shown in Fig. 3. Details are
described briefly in the following.
Trigger 1 (< 1 >)
The triggers as indicated in the status display area and
by the status displays relate to the measurement chan-
nel which is selected by the key below.
If the left arrow of the trigger display is on, this indicates
that the actual pressure is lower than the trigger set
point.
If the right arrow of the trigger display is on, this indica-
tes that the actual pressure is higher than the trigger set
point.
Trigger 2 (< 2 >)
The same as for trigger 1 also applies to trigger 2.
FAIL
The word FAIL comes on in the event of a sensor failure;
see Section 2.9.
DISP
DISP indicates the channel, the values of which are just
being displayed. Here for example TM 1, TM 2 or PM.
HV
The HV (high vacuum gauge) message comes on, when
the high voltage for the PM channel is present.
CORR
The CORR message comes on, when a different type of
gas other than the standard gas „air / nitrogen“ has been
10
Fig. 3 Partial view of the front panel
Key to fig. 3
1 Status display area
2 Bar graph display
3 Digital display
4 Measurement units

selected on parameter page 5.
LOCK
The LOCK message comes on, when the entry of para-
meters via the keyboard has been locked. For this refer
to Section 2.3.9.2.
PARA
The PARA message comes on, when entering instru-
ment parameters. The entered instrument parameters
apply to the currently selected and displayed measure-
ment channel.
2.3.5 Keys TM 1,TM 2 and PM
Pressing key TM 1, TM 2 or PM selects the correspon-
ding measurement channel.The pressure of the selected
measurement channel is then displayed by displays (3/2)
and (3/3).
The trigger and chart recorder outputs of all channels
present is not influenced in any way by the selection of a
particular measurement channel.
2.3.6 Key HV
The HV key (4/1) is used to switch the high voltage for
the PM channel on and off.
After switching on the PM high voltage a value is indica-
ted immediately, provided the PM channel has been sel-
ected. 10 s after switching on the high voltage the instru-
ment checks whether the gauge tube has ignited and
whether the pressure has risen above 5·10-9 mbar. As
long as these conditions have not been met „FAIL“ will be
displayed and the triggers will not be active.
However, if these conditions have been met once after
switching on, the instrument will indicate that it is ready.
Thereafter the triggers are active, independently of the
pressure, cable or sensor conditions until the high volta-
ge is switched off again.
Warning Even in the presence of an error messa-
ge the PM high voltage (3.3 kV) will
remain switched on.
Note
- PENNINGVAC gauges should only be switched on at
pressures below 1·10-2 mbar. Due to the physical prin-
ciple employed, any PENNINGVAC gauge can be swit-
ched on at higher pressures (HV-on).
- After switching on the high tension, the gas discharge
is started in the sensor with a voltage of 3.3 kV. After
successful ignition this voltage is then reduced to an
1.6 kV operating level.This increases the service life of
the sensors, in particular in connection with argon
atmospheres.
When switching on the PENNINGVAC gauge at pressu-
res over 1·10-2 mbar the display will indicate an unspeci-
fied value. Prolonged operation in this unpermitted pres-
sure range may lead to increased contamination of the
gauge.
More details on the operation of this key are given on
parameter page 7 „Switching the PENNINGVAC on and
off automatically“.
11
Fig. 4 Partial view of the front panel
Key to fig. 4
1KeyHV
2KeyPM
3 Key TM 2
4 Key TM 1
5 Status display area
6 Key decrement
6

2.3.7 Key Decrement
The decrement key (5/3) is used for setting up the trig-
gers and other instrument parameters. Each time this
key is pressed, the displayed mode is decremented by 1;
in the case of numeric values the least significant digit is
decremented by 1.
When pressing the decrement key for more than 2 s
while setting up the triggers, the range of values will pass
through rapidly.
2.3.8 Key Increment
The increment key (5/2) is used for setting up the triggers
and other instrument parameters. Each time this key is
pressed, the displayed mode is incremented by 1; in the
case of numeric values the least significant digit is incre-
mented by 1.
When pressing the increment key for more than 2 s while
setting up the triggers, the range of values will pass
through rapidly.
2.3.9 Key PARA
The „PARA“ key (5/1) is used for switching the instru-
ment to the parameter mode, where individual parame-
ters of the instrument may be checked, set up or where
the parameter settings may be locked.
Note
The preselected setting (see setting AUTO.1) for pressu-
re dependent switching of the PENNINGVAC channel
through Thermovac channel 2 is displayed at pressures
above (below) the threshold of the TM 2 channel (PM
channel). When then pressing the key PM (TM 2) the
corresponding pressure reading of the PM channel (TM
2 channel) will be displayed. After 1 minute the display
will automatically revert back to the TM 2 channel (PM
channel).
2.3.9.1 Checking and setting up of the equipment
parameters
The PARA (5/1) key is pressed when wanting to check or
change the settings of the various instrument parame-
ters. The PARA message in the status display area
comes on and the first parameter page of the currently
selected measurement channel is displayed.
Pressing the PARA key once more selects the next para-
meter page.
The currently selected parameter page number is indi-
cated by the bar graph display (2/7). The number of
active bars (starting from the right hand side) corre-
sponds to the number of the currently selected parame-
ter page. For technical reasons only parameter page
numbers starting with No.3 are displayed in this way, i.e.:
3 bars correspond to parameter page 3,
4 bars correspond to parameter page 4 etc.
On the individual parameter pages, the parameters
themselves may be changed by the decrement key (5/3)
and the increment key (5/2). Any entries made via the
decrement (5/3) or increment (5/2) keys become imme-
diately effective.
Note
When no key is operated for approximately 1 minute the
CM 31 will automatically switch back to the measure-
ment mode, whereby the settings which were displayed
at the time of leaving the parameter page are stored.
If no changes in the display are noticeable when opera-
ting the decrement (5/3) or increment (5/2) keys, access
to the parameter entry mode has been locked before-
hand.This condition is also indicated by the LOCK mes-
sage.
The parameter mode may be left by
- operating any measurement channel selection key or
- automatically after displaying the last parameter page.
All changes will become stored and active automatically.
12
Key to fig. 5
1 Key PARA
2 Increment parameter
3 Decrement parameter
Fig. 5 Partial view of the front panel

A difference is made between two levels of parameters.
Parameter level 1
Entering the parameter level 1 the following will be
shown:
Page 1
The current trigger relays value for trigger 1.
If no sensor, or a faulty sensor is connected to theTHER-
MOVAC channel or if the high voltage for the PENNING-
VAC channel is off, the two arrows of trigger 1 will be
flashing.
When the TM-channel is ready, or if the PM high voltage
is on, the left hand arrow will flash when the current trig-
ger value is lower than the measured pressure.
When the THERMOVAC channel is ready, or if the PM
high voltage is on, only the right hand arrow will flash
when the current trigger value is higher than the measu-
red pressure.
Trigger levels when shipped:
TM 5·10-3 mbar / 3.7·10-3 Torr
PM 1·10-8 mbar / 7.5·10-9 Torr
Page 2
Current trigger relays value for trigger 2.
Here the same applies as for page 1.
Page 3
Setting up the operating modes „Level trigger“ or „Inter-
val trigger“.
The diagrams given in Fig. 6 provide an overview of the
two trigger modes.
L Level trigger
Both trigger outputs are operated independently of
each other. Thresholds may be set up either within
the range between 1·10-8 and 1·10-2 mbar for PM
measurement channel or for TM measurement chan-
nel between 5·10-3 and 500 mbar.
Pressure dependent hysteresis is shown in tables 3
and 4 or tables 7 and 8 of Section 2.10.
I Interval trigger
Operation of the two triggers (trigger 1 and trigger 2)
is linked. When entering the thresholds the following
condition must be met:
Trigger threshold 1 < trigger threshold 2
The set up interval (difference between threshold 1
and 2) cannot decrease 5 % of the value for threshold
1.
In this mode, output 2 operates as a level trigger and
output 1 operates as the interval trigger.
When switching from the level trigger mode to the inter-
val trigger mode threshold 1 must be < threshold 2. If it
is not
L(for Level) and the symbol
will be displayed referring to the Operating Instructions.
At the same time the digits 1 and 2 of the < 1 > or < 2 >
display will be displayed flashing.
The condition of trigger threshold 1 < trigger threshold 2
must be met first before switching over.
Setting when shipped: L (Level trigger)
13
Fig. 6 Level trigger and interval trigger diagram

Page 4
Correction for the type of gas
GAS.n2 ‰Air / Nitrogen (N2)
GAS.Ar ‰Argon
Setting when shipped: Air / Nitrogen
For a more accurate determination of the true pressure
for gases other than air or N2in the system, the display-
ed value has to be multiplied by a factor which is cha-
racteristic for the other type of gas.
Gas Correction factorr
————————————————————————
O20,88 The correction factors
He 4,7 refer to the setting
H22,28 for GAS.n2 in each case.
Ne 2,16
Page 5
Software release number and locking (LOCK); refer also
to Section 2.3.9.2.
The transition from the parameter mode to the normal
measurement mode is made by pressing the key of the
desired measurement channel (TM 1, TM 2 or PM) or by
pressing the PARA key.
Parameter level 2
Parameter level 2 is called up by pressing the incre-
ment (2/13) key when parameter page 5 is being dis-
played.
Parameter level 2 contains the following:
Page 6
Units of measurement TORR, PA, MICRON, MBAR
The currently active unit flashes.
Note
The unit which is set up here, applies to all three connec-
ted measurement channels.
Supplied condition: MBAR (230 V model)
TORR (100 V or 120 V model)
Even when selecting the unit „MICRON“ for a TM chan-
nel, the pressure readings for the PM channel will always
be in „TORR“.
If the TM channels are to be set to „MICRON“ this can
not be done via the PM channel. This is only possible
when having previously selected a TM channel.
Page 7
Note
On parameter page 7 of instrument parameter level 2
there are different displays for the THERMOVAC channel
and the PENNINGVAC channel.
Page 7 for theTHERMOVAC channel
Filament material of the connected sensor (FILAMENT).
FIL tu Tungsten TR 211, TR 201 and TR 205
FIL ni Nickel TR 206
FIL pt Platinum TR 216
Setting when shipped: FIL tu
Page 7 for the PENNINGVAC channel
Instrument parameter page 7 is used for automatic, pres-
sure dependent switching of the PENNINGVAC channel.
After calling up instrument parameter page 7 the display
will indicate AUTO.0 or AUTO.1
AUTO.0 The high voltage may be switched on and off
via the „HV“ key or via the external input HV-
ON.The status of the PENNINGVAC channel
is not controlled via the measurement chan-
nel TM 2.
AUTO.1 Depending on the pressure the high voltage
is switched on and off through measurement
channel TM 2.The high voltage may be swit-
ched off and on at any time by pressing the
„HV“ key or through the external input HV-
ON, provided the pressure is below 1·10-2
mbar.
The threshold pressure for
- switching on the high voltage is:
< 1·10-2 mbar = 7.5·10-3 Torr = 1 Pa = 8 Micron
- switching off the high voltage is:
> 5·10-2 mbar = 3.75·10-2 Torr = 5 Pa = 37 Micron
In the case of automatic operation, the pressure display
is switched to the best measurement channel (TM 2/PM)
depending on the pressure. In the event of a faulty sen-
sor in channel TM 2 the high voltage has to be switched
on by the operator.
The display switches from the THERMOVAC channel to
the PENNINGVAC channel at a pressure of < 3·10-3
mbar (2.5·10-3 Torr) and from the PENNINGVAC channel
to the THERMOVAC channel at a pressure of > 5·10-3
mbar.
Having actuated the keybord the change-over can be
delayed by 1 min.
Setting when shipped: AUTO.1
Page 8
Equipment parameter page 8 is used for switching the
numerical display from standard resolution (2-digit man-
tissa) to high resolution (3-digit mantissa).
Std Standard resolution 3.0 -2
HIGH High resolution 3.00-2
For this refer to tables 3 and 4 in Section 2.10.1 or tables
7 and 8 in Section 2.10.2.
14

Page 9
Note
On parameter page 9 of instrument parameter level 2
there are different displays for the THERMOVAC channel
and the PENNINGVAC channel.
Page 9 for theTHERMOVAC channel (TM)
Cable length adjustment for the THERMOVAC gauges.
Note
Equipment parameter page 9 is used to enter the length
of the cable for THERMOVAC gauge heads.
After calling up parameter page 9 the display will indica-
te „CL xxx“.
CL Cable length
xxx Length in m
By operating the increment or decrement keys it is pos-
sible to enter cable lengths in the range between 0 m and
100 m in 5 m increments (5 m, 10 m, 15 m, 20 m, 25 m
etc.).The default setting is 5 m.
Note
Intermediate values must be rounded off.
The values only apply to standard cables 6 x 0.14 mm2.
Note
When combining a TR 211 gauge from series B1 or later
or a TR 215 / 216 and TM channel from software revisi-
on 2.0 or later the lenght of the gauge head cable is auto-
matically accounted for by means of automatic cable
lenght alignment. „CLA“ will be displayed on parameter
page 9.
Page 9 for the PENNINGVAC measurement
channel (PM)
Adjustment of the analogue output (for this also see Sec-
tion 2.10.3).
Seven different ranges can be set up.
Logarithmic output characteristic:
Ano-8 : log 1·10-9 - 1·10-2 mbar (1.43 V / decade)
Linear output characteristic:
0 0,1 1 ... 5 V ... 10 V
Anl-7 : 1·10-9 1·10-8 1·10-7 mbar
Anl-6 : 1·10-8 1·10-7 1·10-6 mbar
Anl-5 : 1·10-7 1·10-6 1·10-5 mbar
Anl-4 : 1·10-6 1·10-5 1·10-4 mbar
Anl-3 : 1·10-5 1·10-4 1·10-3 mbar
Anl-2 : 1·10-4 1·10-3 1·10-2 mbar
Page 10 for the THERMOVAC measurement
channel (TM)
Adjustment of the analogue output (for this also see Sec-
tion 2.10.2).
Eight different ranges can be set up.
Logarithmic output characteristic:
Ano-3 : log 1·10-3 - 1000 mbar (1.67 V / decade)
Ano-4 : log 5·10-4 - 1000 mbar (1.587 V / decade)
Linear output characteristic:
0 0,1 1 ... 5 V ... 10 V
Anl-2 : 1·10-4 1·10-3 1·10-2 mbar
Anl-1 : 1·10-3 1·10-2 1·10-1 mbar
Anl+0 : 1·10-2 1·10-1 1·10+0 mbar
Anl+1 : 1·10-1 1·10+0 1·101mbar
Anl+2 : 1·10+0 1·1011·102mbar
Anl+3 : 1·1011·1021·103mbar
2.3.9.2 Locking of parameter settings
By locking the parameter settings, the entered and sto-
red parameters may be protected against any unquali-
fied changes.
When parameter page 5 is displayed (software release
number) pressing the PARA key of the TM 1 measure-
ment channel for more than 5 seconds will lock up all
parameters and prevent any further parameter changes.
The „LOCK“ message will come on. With the „LOCK“
message on, it is only possible to check the settings of
the parameters. However, keys TM 1, TM 2 and PM
remain accessible.
Unlocking is only possible by displaying the number of
the software release of the TM 1 measurement channel
once more (parameter page 5) and by pressing the
PARA key for more than 5 seconds.
15

2.4 Supply and socket
connections on the rear
All supply connections and sockets are located on the
rear. These are shown in Fig. 7.
2.4.1 AC power supply
Connection to the AC power and selection of a different
line voltage setting and exchanging the line fuse of the
CM 31 is described in Section 2.2.
2.4.2 Connection of the
THERMOVAC gauge
The THERMOVAC gauge heads for measurement chan-
nels TM 1 and TM 2 are connected to sockets (7/4) and
(7/10) respectively.
2.4.3 Connection of the
PENNINGVAC gauge
The PENNINGVAC sensor is supplied
with a high tension via socket (7/9).
(3.3 kV ignition voltage, 1.6 kV operating
voltage; Ri= 7.7 MΩ)
This socket is wired as follows:
Inner conductor Positive high voltage
Outer conductor Return and screen
2.4.4 Screw terminal outputs for the THER-
MOVAC channels
The connections are carried via two terminal strips. One
4-way terminal strip (7/6) or (7/7) above, and one 8-way
terminal strip (7/3) or (7/12) under the gauge head
connector. Those terminal strips which are above each
other are always related to one THERMOVAC channel.
The wiring is the same for both measurement channels
but the numbering of the pins is different.
16
Key to fig. 7
1 Ground (potential equalization for CM 31)
2 Connection for RS 232 C interface
3 Connection for channel TM 1 (triggers 1
and 2 and ready indicator)
4 Connection for THERMOVAC gauge head
(TM 1 channel)
5 AC power socket
6 Connection for channel TM 1
(Chart recorder output)
7 Connection for channel TM 2
(Chart recorder output)
8 Connection for channel PM (Chart recor-
der output and external HV ON/OFF)
9 Connection for PENNINGVAC gauge head
10 Connection for THERMOVAC gauge head
(TM 2 channel)
11 Connection for channel PM (triggers 1 and
2 and ready status indicator)
12 Connection for channel TM 2 (triggers 1
and 2 and ready status indicator)
S1 = TM 1 channel
S2 = TM 2 channel
Note
The designations of the terminals shown in this
illustration correspond to the DIN regulations.
Due to limited space the figures are neither
indicated at the back of the instrument nor on
the terminal strip.
Fig. 7 CM 31 - Rear view
CE

The 4-way terminal strip is wired as follows (Fig. 7)
TM 1 TM 2 Signal
————————————————————————
11 111 Trigger threshold (TRG) in preparation
12 112 Trigger threshold (ground) in preparat.
31 131 Chart recorder output 0 to 10 V (REC)
32 132 Chart recorder output (ground)
The 8-way terminal strip is wired as follows (Fig.7)
TM 1 TM 2 Signal Contact symbol
————————————————————————
82 85 C Ready
83 86 n.o. (open)
41 44 n.c. (closed)
42 45 C Trigger 1
43 46 n.o. (open)
51 54 n.c. (closed)
52 55 C Trigger 2
53 56 n.o. (open)
n.c. Normally closed (resting contact)
n.o Normally open (operating contact)
C Common (Centre contact)
Note
The 8-way socket is specified for a max.permissible ope-
rating voltage of 250 V AC and 50/60 Hz with reference
to the safety ground conductor.
2.4.5 Screw terminal outputs for the PEN-
NINGVAC channel
The connections are carried via two terminal strips. One
5-way terminal strip (7/8) above, and one 8-way terminal
strip (7/11) under the gauge head connector.
The 5-way terminal strip is wired as follows (Fig. 7)
PM Signal
————————————————————————
233 + 24 approx. (Ri= 680 Ω)
for external contact on 211
211 HV control input for PM (HV ON)
212 Ground for HV control input
231 Chart recorder output 0 to 10 V (REC)
232 Ground for chart recorder output
For the PENNINGVAC channel the wiring of the 8-way
terminal strip (7/11) is the same as for the 8-way termi-
nal strips (7/3) and (7/12) for theTHERMOVAC channels
but the numbering of the pins is different!
The 8-way terminal strip is wired as follows (Fig. 7).
PM Signal Contact symbol
————————————————————————
182 C Ready
181 n.o. (open)
141 n.c. (closed)
142 C Trigger 1
143 n.o. (open)
151 n.c. (closed)
152 C Trigger 2
153 n.o. (open)
n.c. Normally closed (resting contact)
n.o. Normally open (operating contact)
C Common (Centre contact)
2.4.6 RS 232 C interface
The connections are made through a 9-way Sub-D
connector (3/2).
The interface socket on the A-series instruments is wired
as follows:
Pin No. Designation Remarks
————————————————————————
1 Not used
2 TxD Transmission data (output)
3 RxD Receive data (input)
4 Not used
5 GND Reference ground for signals
6 DTR Is pulled high (+ 8 V approx.)
when the mains voltage is
applied to the instrument.
7 Not used
8 RTS Is pulled high (+ 8 V approx.)
when the mains voltage is
applied to the instrument.
9 Shield Ground connection for cable
shield
17

2.5 Installing the instrument
The CM 31 has been designed to operate reliably under
all normally encountered industrial conditions (see Sec-
tion 1.2.9).
The instrument is supplied with a rugged table-top hou-
sing. The metal housing is provided with ventilation slits
on the top and bottom. When installing the instrument
within a cabinet, sufficient ventilation must be ensured.
For this, also refer to Section 1.2.9 „Ambient conditions“.
The metal housing also reliably protects the instrument
against electromagnetic interferences (EMI). However,
the CM 31 should be installed away from strong magne-
tic fields, large transformers and motors etc., so that the
instrument cannot be influenced.
2.5.1 Installation
Note
When installing the CM 31, care should be taken so as
not to obstruct the ventilation slits in any way. Also ensu-
re a sufficient throughput of air.
2.5.2 Rack installation
The CM 31 is delivered for installation into a 19“ rack
having 3 height units.
It is inserted into the rack and secured by screwing in
four mounting screws through the holes on front panel.
Mounting screws are included.
2.5.3 Panel installation
The CM 31 is delivered ready for panel mounting. The
required panel cut out is given in Fig. 8.
2.5.4 Using the CM 31 as a table-top
instrument
When using the CM 31 as a table-top instrument a sup-
port stand (Ref.No.200 60 900) may be fitted to the bot-
tom of the instrument. The support is inserted from the
rear into the lowermost groove of the corner profile and
is then pushed to the front until it engages.
The four adhesive feet (Ref. No. 229 48 120) are atta-
ched under the support stand and under the rear of the
instrument.
2.6 Checking the equipment
functions
2.6.1 TM measurement channels
The THERMOVAC measurement channels are supplied
factory-aligned and does not require any maintenance.
Test gauge T 210 may be used to check important equip-
ment functions.The test gauge is a gauge head simula-
tor for a THERMOVAC gauge head, but it does not sup-
ply calibration values.
By operating the potentiometer it is possible to simulate
any pressure within the range between 5·10-4 mbar and
atmosphere.
This is especially useful for checking trigger thresholds
and trigger reactions in vacuum systems since this
checking can be carried out without starting up the vacu-
um pumps.
In the event of a fault in the measurement system test
gauge T 210 may be used to determine whether the fault
is with the gauge head, the gauge head cable or the CM
31 itself.
18
Fig. 8 Dimensional drawing and panel cutout (dimensions in mm)

2.6.2 PM measurement channel
The PENNINGVAC measurement channel is supplied
factory-aligned and does not require any maintenance.
Test gauge T 35 may be used to check important equip-
ment functions.The test gauge is a gauge head simula-
tor for the PENNINGVAC gauge head. Different pressu-
re values are simulated via integrated resistors and are
available at three plug sockets.
The test values are indicated on the gauge head.
In the event of a fault in the measurement system test
gauge T 35 may be used to determine whether the fault
is with the gauge head, the gauge head cable or the CM
31 itself.
2.7 Alignment of the THER-
MOVAC gauge heads
Aging and contamination of the filament within the gauge
head will impair the accuracy of the pressure readings.
Therefore it is recommended to align the THERMOVAC
gauge heads from time to time when appropriate. This
alignment is carried out as follows:
Vent the vacuum system and adjust the 100 % potentio-
meter on the THERMOVAC gauge head so that the fol-
lowing bargraph display is obtained:
Note
In order to ensure a stable but none-the-less accurate
alignment of the 100 % value, the alignment potentiome-
ter (100 %) should be turned further by 90°in the clock-
wise direction after the last segment of the bargraph has
come on. When doing so, the right arrow (overrange)
may just come on.
Evacuate the vacuum system down to a pressure 5·10-4
mbar and then adjust the „0“ potentiometer on the
THERMOVAC gauge head so that the following bargraph
display is obtained:
Vent the vacuum system once more and check the
100 % setting once more. If required correct any possi-
ble deviations.
If it was necessary to correct the 100 % setting, Zero ali-
gnment must be repeated.
Note
With the Torr setting the bar +3 is permanently switched
off.
2.8 Switching off
The instrument is switched off simply by disconnecting
the power cord.
19
Alignment
too high
Alignment
exact
Alignment
too low
Alignment
too high
Alignment
exact
Alignment
too low

2.9 Status messages
The COMBIVAC CM 31 is able to display a variety of sta-
tus messages.
FAIL FAIL indicates that there is a fault in the sensor.
If a fault is present when selecting a THER-
MOVAC measurement channel, one of the fol-
lowing error messages is displayed:
No sensor
Fault cause:
- Gauge head cable disconnected
- Damaged cable
- Sensor can not be identified
- Missing sensor
Filament broken
Fault cause
- Filament faulty
FAIL The following applies to the PENNINGVAC
channel:
HV (high voltage) was switched on at a pres-
sure below 5·10-9 mbar / Torr (5·10-7 Pa).
Interrupted gauge head cable.
Sensor not connected.
Note
When switching on the high voltage the mes-
sage „FAIL“ will appear after 10 s until the gau-
ge tube has ignited and provided the pressure
exceeds 5·10-9 mbar.
FAULT A fault has occurred during the execution of the
microprocessor program due to exceptionally
strong electromagnetic interferences or a brief
mains failure (1 to 3 seconds), for example. In
this case the instrument or the affected mea-
surement channel is reset to a stable through a
Watchdog function:
- Display: Status FAULT, all other segments
may flash
- Chart recorder output is set high to 10.2 to
10.6 V.
- The contact of the Ready relay is opened,
trigger relays are set to the rest position.
Remedy:
Switch the instrument off (disconnect from the
mains). Reconnect after 5 s at the earliest.
This symbol indicates that the CM 31 should
be operated according to the Operating
Instructions as the instrument has been opera-
ted incorrectly.
For example.: L
The triggers are set to the interval mode, but
threshold 1 is higher or equal to threshold 2.
This symbol will also appear when operating a
key which - in that particular operating mode -
has no function. This symbol is automatically
erased after some time.
This symbol indicates the presence of a fault
within the instrument.
Initialization text when changing the sensor for
the TM channel.
The following applies to the PENNINGVAC channel:
Off
Cause:
- High voltage has not been switched on.
20
FAULT