Instruction Manual

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www.vtsgroup.com Page 10 of 16 ver. 2.0 (11.2021)
It is recommended that devices on the MODBUS (RS485) are connected in a daisy-chain
configuration, whereby 120R terminating resistors should be connected between A and B
lines of the bus at both ends of the chain (close to the outer devices). This resistor is built-
in in the RH&T-SENS-D-MODBRTU transducer and can be switched on using the no. 1
switch on the configuration DIP-switch (see section 3.4).
Moreover, shielded cables should be used when the device is operated in high interference
environments and the shield should be connected to the nearest PE point on the power
supply side.
4. MODBUS protocol
4.1. Register map
Register
no.
R/W
Name
Values
Notes
0x0000
R
RH_REG
0 ÷ 1000
Relative humidity (1=0.1%; 1000=100%)
0x0001
R
TEMP_REG
-4000 ÷ 12380
Temperature [ºC] (1=0.01ºC) with sing
0x0002
R
TEST_VAL_REG
1000 (0x3E8)
Test value – to verify the correctness of
register readings
0x0003
RW
PASS_REG
1234 (0x04D2)
password register
0x0004
RW
COMMAND_REG
1 / 2 / 3 / 4 / 5 /
6
command register
0x0005
RW
PARAM_REG
Refer to
command table
parameter register
0x0006
R
--
0
reserved
0x0007
R
--
0
reserved
0x0008
R
--
0
reserved
0x0009
R
--
0
reserved
0x000A
R
STATUS_REG
0 / 1 / 2
Status register (0: NO SENSOR; 1: SENSOR OK,
2: ERROR)
0x000B
R
DEV_ID_REG
0xC100
Device identification
0x000C
R
SOFT_VER_REG
0 – 0x9999
Software version
(e.g. 0x3210 means software 3.21a)