INFICON HLD6000 Refrigerant Leak Detector Interface Description - Manual (Page 7)

ASCII Protocol 7
2 ASCII Protocol
2.1 Communication Parameters
2.2 Command Format
In ASCII protocol any command starts with « * » (ASCII code 42dec/2Ahex) and is
finished with the end sign CR (ASCII code 13dec/0Dhex). 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 (The short
form is here written in capitals but the SW don’t difference upper and lower cases).
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 the requested data, „ok“ or „EXX“ (in case of an
error). For a list of all error messages
see chapter 2.5, page 15 . The transmission
can be cancelled and the receive-buffer will be cleared with ESC (ASCII code 27dec/
1Bhex), ^C (ASCII code 3dec/03hex) or ^X (ASCII code 24dec/18hex).
Some commands can be used as queries, some can be used to set menu parameter
and some can be used for both. A query is marked by a „?“ (ASCII code 63dec/
3Fhex) after the command; for setting data the command has to be followed by the
new value to be set.
Parameter can be Boolean or numerical:
Notice Always use a point as the decimal marker. If a comma is used during
numerical data entry, the conversion of the number is cancelled at this
point and only the integer part of the number will be used.
Timing recommendations for the PC/PLC - Program:
Sample rate > 100 ms
Timeout between request to and answer from Device: 1500 ms
After sending a command the answer must be waited for before sending a new
command. Otherwise the receive buffer may be overwritten.
Data format
19200 baud, 8 data bits, no parity, 1 stop bit
Boolean 0 / 1 or OFF / ON
Numeric representation format: integer, real (15.6) or exponential (4.5E-7)
Format: [space] [sign] [ddd] [.] [e[sign]ddd] (d:digit)