5
Sent request and response have syntax: ADDRESS OF DEVICE – FUNCTION – Modbus CRC
Supported functions
03 (0x03): Reading of 16-bit registers (Read Holding Registers)
04 (0x04): Reading of 16-bit input gates (Read Input Registers)
16 (0x10): Setting of more 16-bit registers (Write Multiple Registers)
Jumper and button
Jumper and button are located next to connection terminals. If communication protocol
Modbus is selected the function of jumper and button is as follows:
• Jumper opened – transmitter memory is protected from writing, from transmitter side it is
only enabled to read measured value, writing to memory is disabled (no change of
transmitter address, communication speed and LCD setting is enabled)
• Jumper closed – writing to transmitter memory is enabled by means of User’s software
• Jumper closed and button pressed for longer than six seconds – causes restoring of
manufacturer setting of communication protocol, i.e. sets Modbus RTU communication
protocol, device address sets to 01h and communication speed to 9600Bd (after button press
there is “dEF” message blinking at LCD display. Six seconds later message “dEF” stays
shown, it means manufacturer setting of communication protocol is done).
• Jumper opened and button shortly pressed – transmitter goes to Info mode, see chapter „Info
mode
“
Modbus registers of the device
Variable Unit Address
X
Format Size Status
Measured temperature [°C] 0x0031 Int*10 BIN16 R
Measured relative humidity [%] 0x0032 Int*10 BIN16 R
Computed value
*
[°C] 0x0033 Int*10 BIN16 R
Address of transmitter [-] 0x2001 Int BIN16 R/W*
Code of communication speed [-] 0x2002 Int BIN16 R/W*
Serial number of transmitter Hi [-] 0x1035 BCD BIN16 R
Serial number of transmitter Lo [-] 0x1036 BCD BIN16 R
Version of Firmware Hi [-] 0x3001 BCD BIN16 R
Version of Firmware Lo [-] 0x3002 BCD BIN16 R
Explanation:
• * to choice of computed value type use User’s software
• Int*10 register is in format integer*10
• R register is designed only for reading
• W* register is designed for writing, for more details see chapter description of
communication protocols
•
X
register addresses are indexed from zero – register 0x31 is physically sent as value
0x30, 0x32 as 0x31 (zero based addressing)
Note: In case there is a need for reading of measured values from transmitter with higher resolution
than one decimal, measured values in transmitter are stored also in „Float“ format, which is not
directly compatible with IEEE754.
Protocol compatible with Advantech-ADAM standard
Control units communicate on master-slave principle in half-duplex operation. Only master
can send requests and only addressed device responds. During sending request any of slave devices
should respond. During communication data is transferred in ASCII format (in characters). Each
Byte is sent as two ASCII characters. Transmitter supports communication speed from 1200Bd to
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