User Manual SERVOPRO PLASMA Trace N
2
Analyzer
APPENDIX 4
72
• Baud rate: 9600
• Parity bits: none
• Data bits: 8
• Stop bits: 1
1.2. Transmission protocol
The different parameters are transmitted in the following order:
ppm value sign, ppm value, TAB, flow, TAB, flow counts, TAB, cell counts TAB,
status and range, TAB, checksum, CR.
Each parameter is formatted as followed:
• PPM value sign: 1 byte equal to “+” or “-” in ASCII, depending on the polarity of
the ppm value;
• PPM value: 6 bytes in ASCII (3 digits before the dot and two after);
• Flow: 6 bytes in ASCII (3 digits before the dot and two after);
• Flow counts: 8 bytes in ASCII;
• Cell counts: 8 bytes in ASCII;
• Status and range: bitwise (logical on 8 bits);
bit 7: alarm 2 1 if alarm 2 is ON
bit 6: alarm 1 1 if alarm 1 is ON
bit 5: low flow 1 if there is a low flow error
bit 4: plasma status 1 if there is a plasma off error
bit 3: system status 1 if there is a low flow, plasma off, underscale or
overscale error
bit 2, and 0: range in use 001 = range 1 (ex: 0-1 ppm)
010 = range 2 (ex: 0-10 ppm)
100 = range 3 (ex: 0-100 ppm)
Each value is separated by a TAB character. The end of one transmission (packet or frame) is
indicated with a carriage return.
The checksum is the arithmetic sum of every transmitted byte (excluding TAB bytes). The
checksum may be used to verify the data integrity.
Example : the ppm value is 40.1, the flow is 75.0 ml min
-1
(75 cc/min), the flow counts are
8388600, the cell counts are 190011, the range used is the first one (0-1 ppm), there are no
alarm, but there is a low flow error.
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