INFICON UL1000 Helium leak detector Interface description - Manual (Page 5)

Interface Description
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1 Interface Description
1.1 Preface
The RS232 porotocol uses an ASCII format: so every leak detector can be controlled
with a simple terminal programm.
Choose the interface porotocol „ASCII“ to connect the leak detector with the
computer via RS232 interface.
In case the leak detector shall also be controlled via computer (START, STOP,
ZERO, etc.), set the “control location” at the leak detector to „RS232“ or „local and
RS232“.
The following parameter of interfaces are in use:
19200 baud, 8 databits, 1 stopbit, no parity.
1.2 Interface Connecting Cable
The RS232 interface is wired as data communication equipment (DCE). The leak
detector provides a 9-way sub-D socket for the connector. The signals are assigned
as follows:
The other pins are not being used.
The levels on the RS232 interface are defined as follows:
1.3 Command Format
In ASCII protocol any command starts with « * » (ASCII code 42dec) and is finished
with the end sign selected (e.g. CR). There is no differentiation between upper and
lower case. A blank is required between the command and the parameter, no other
blanks are allowed.
There is a short and an extended form of the command. Either the short or the
extended command must be used, no other abbreviations are allowed. Command
Words have to be separated by a colon. A command can be composed of up to three
words. Parameters have to be separated by a comma.
Each command is answered with „ok“ or „EXX“ (in case of an error). For a list of all
error message see section 4.1.3. The transmission can be cancelled with ESC
(ASCII code 27dec), ^C (ASCII code 3dec) or ^X (ASCII code 24dec).
Pin Name Signal
2 RxD Receive data (leak detector
→ PC)
3 TxD Transmit data (PC
→ leak detector)
5 GND Reference Ground
Level Low (L) High (H)
Voltage Range -3 V … -25 V 3 V … 25 V
Logic State logical 1 logical 0
Level Designation Mark Space