INFICON T-Guard Leak Detection Sensor Interface description - Manual (Page 25)

RS232 Binary Interface Protocol
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4 RS232 Binary Interface Protocol
The binary protocol is machine readable, secure and fast. INFICON also uses this
for analysis in its quality control and trouble shooting during manufacturing and
service.
4.1 Communication Parameters
4.2 Binary Command Format
When using the binary protocol the command sent to T-Guard™ Leak Detection
Sensor always starts with STX (0x05).
It is followed by a byte which indicates the length of the telegram (including start byte
and checksum). The next byte is the command number. The command byte may be
followed by additional information (parameter and/or data). Please refer to
"Command List Binary Mode" (section
4.2.1 ) for detailed information about command
number, parameter and data format. Every telegram ends with a checksum. The
checksum is the sum of all bytes, excluding the checksum byte, modulo 256
(decimal).
T-Guard™ Leak Detection Sensor replies to every valid command with an
acknowledgement. All answers start with the length byte followed by the command
number, additional data (optional) and the checksum.
In case of an error, T-Guard™ Leak Detection Sensor answers with an error byte
instead of the command number (refer to "Error Messages Binary Mode" in section
4.3 ).
The time out to receive data between 2 signs is 1000 ms.
Tip: When programming in LabView
TM
, you want to turn off the usage of termination
characters in the VISA serial module. Otherwise a value of 10 will not show up.
Data Format
baudrate
19,200
float 4 Bytes, IEEE754 (± 10±38), 3 Byte Mantissa,
1 Byte Exponent/Sign
unsigned long int [ul int]: 4 Bytes, integer without algebraic sign MSB …
LSB (0 … 4294967295)
unsigned short int [usint]: 2 Bytes, integer without algebraic sign MSB …
LSB (0 … 65535)
signed short int 2 Bytes, integer with algebraic sign MSB …
LSB (-32768 … 32767)
unsigned char [uchar]: 1 Byte, integer without algebraic sign (0 …
255)
unsigned char [uchar]: 1 Byte, character ASCII Code (0 … 255)
stop bit 1 stop bit