LEYBOLD 157 89, Руководство пользователя

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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
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