Technical Manual 9200
REF: 380/5 15
4. RS485 frame protocol
Goal: read viscosity and Pt100 values using RS-485 communication
S: send from the console to the board
R: response from the board to the console
Viscosity: viscosity in the unit displayed on the 9200 screen (cP, P, mPa.s or Pa.s)
Pt100: value in the unit displayed on the 9200 screen (°C or °F) of the temperature read by the probe
when there is one
COM port characteristics:
Speed: 9600 bits/s Number of bits: 8 Parity: none Stop bit: 1
Generic frame format (all the data in the frames are in Hexadecimal)
S = SN 04 XX XX YY YY <CRC-16>
R = SN 04 AA {DATA} <CRC-16>
SN: slave number 04: reading function
XX XX: starting point for the addresses to be read YY YY: number of words to be read
AA: read bytes number DATA: content of all the asked addresses
<CRC-16>: checksum Modbus RTU on 16 bits (can be automatic if PLC or software is compatible)
NB: 1 word = 2 bytes
List of addresses:
The viscosity value read through the RS-485 is the viscosity displayed on the 9200 main screen
multiplied by a factor which depends of the viscosity range of the unit.
Therefore, the viscosity read through the RS-485 has to be divided by a factor in function of its full-
scale range and which is indicated in the table below:
Full scale range Multiplied factor
0 to 3,999 mPa.s 1,000,000
4,000 to 39,999 mPa.s 10,000
Above 40,000 mPa.s 1,000
Data to read
Address in
Hexadecimal
Number of
words
Multiplied factor of
the data received
Frame to send with a
unit at slave address 01
Viscosity
(in cP, P
mPa.s or Pa.s)
0x 00 14
2 words
4 bytes
(UINT_32)
1,000
or 10,000
or 1,000,000
(see table below)
01 04 00 14 00 02 31 CF
Temperature
(in °C or °F)
0x 00 12
2 words
4 bytes
(INT_32)
100,000 01 04 00 12 00 02 D1 CE
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