Notes On Sensors With Modbus-Rtu; Serial Format And Transfer Rate; Overview Of Available Modbus Registers - Thies CLIMA Hygro-Thermo Transmitter-compact Instructions For Use Manual

6 Notes on sensors with MODBUS-RTU

6.1 Serial format and transfer rate

The following parameters are applicable for data transfer via the RS-485 interface on the MODBUS
sensors:
half-duplex with twin wires
19200 bit per second
8 data bit
no parity testing
1 stop bit
monitoring interval (recommended) > 1s
a maximum of 8 registers per query

6.2 Overview of available MODBUS registers

All registers can be read using the MODBUS function code "03" (Read Holding Register) or the
MODBUS function code "04" (Read Input Register). Table 1 shows all available registers for
MODBUS sensors:
16 bit register-no.
0000-0001
0002
0003-0004
0005
0006 - 0007
0205
Alarmcode:
Temperature channel:
0 = no alarm, the temperature value is within
the limits
1 = temperature measurement range exceeded
2 = below temperature measurement range
3 = no sensor signal
4 = short circuit at PT1000 (resistance < 500 Ω)
format
float (32bit)
int (16bit)
float (32bit)
int (16bit)
long (32bit)
int (16bit)
Table 1: MODBUS Register
Table 2: alarm codes humidity and temperature
6 - 14
value
temperature in °C
alarm code temperature
humidity in % r.h.
alarm code humidity
serial number sensor
MODBUS address
Humidity channel:
0 = no alarm, the humidity value is within the
limits
1 = humidity meas. range exceeded (=100% r.h.)
2 = below humidity meas. range (= 0% r.h.)
3 = no sensor signal
4 = humidity sensor defective
read-only
read and writeable
020727/08/13