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vsh-de-130326
4.2.2
Communication Protocol
Communication is carried out according to the Thyracont protocol. The
commands are sent as ASCII-code in the following command frame:
Address
Code
Data
cks
CR
Address:
3 Bytes, decimal; address space RS485: 001 – 999
Code:
1 Byte, command parameter, upper case character for read
command, lower case character for write command
Data:
data field, max. 6 Bytes; can be absent depending on code
cks:
1 Byte, checksum, defined as sum over all Bytes of the fields
address, code and data, modulo 64 plus 64.
CR:
Carriage Return (0Dh, 13d)
Data Formats:
BOOLEAN
1 Byte
STRING:
max. 6 Bytes
UNSIGNED INT:
6 Bytes with leading zeros
FLOAT:
6 Bytes, exponential format
4 Bytes mantissa (means mantissa value x 1000)
2 Bytes exponent, offset 20
FLOAT-values are transmitted in hPa (mbar)!
Example: Value "460016" in a float type data field means 4.6x10
-4
mbar.
Interface-Parameter:
9,6 / 14,4 / 19,2 / 38,4 / 57,6 / 115,2 kBit/s, 8 data bits, 1 Stopbit, no parity
When powered on the transducer starts with 9,6 kBit/s. If a tele-
gram with different baud rate is received, the transducer will au-
tomatically adapt to it. For this automatic baud rate adaption a
maximum of two telegrams of type "Type Request" or "Measure-
ment Request" is required.
4.2.3
Survey of Commands
The transducer responds to type queries, measurement queries, commands for
degas (chapter 4.4) , adjustment (chapter 4.5) and for setting gas correction
factors (chapter 4.6).
Programming of the two relay switchpoints is also done via RS485 (chapter 4.7).
Further special parameters can be configured, which determine the general
behaviour of the sensors (chapter 4.8 and 4.9).
Summary of Contents for VSH88D
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