Introduction - Features - Device working information - Supported MODBUS functions

Introduction


IOMOD HT is used for temperature and humidity data monitoring and relay control over Modbus. Device is also capable of switching relays automatically (thermostat function) as configured.

 

 

Features


• Temperature and humidity sense with ±0,1 % and ±0,1 °C accuracy;
• Temperature sensing range from -10 up to 60 °C;
• Humidity sensing range from 0 to 100%;
• Two Relays which can be configured to turn on automatically on humidity or temperature triggers (only Advanced version);
• Relays automation configuration over USB or Modbus;
• Configurable Modbus settings, such as Slave ID, Baudrate, Parity and stop bits, RS485 terminating resistor, etc.
• Firmware Upgrade over USB;
• Two connectors for power supply and for RS485, for easier device connection on one line;

 

Device working information


IOMOD uses Modbus (RTU) protocol over RS485 connection, which can be used with cable length up to 1500 meters and connect up to 30 devices on one line. Default Modbus settings are: 9600 baudrate, 8N1, Slave address - 1.
To read temperature and humidity, user can use device with default settings without configuring it. To read humidity, send 04 Modbus command (Read Input Registers) with resolution of first register (0). Returned value will be measured in % and will be multiplied by 10, to show one decimal place. To read temperature, send 04 (Read Input Registers) with resolution of second register (1).
Returned value will be measured in °C and will be multiplied by 10. To enable thermostat function, user can configure device over USB or over MODBUS. Configurable options shown in table below.

 

CONFIGURABLE OPTIONS OVER USB OVER MODBUS
Slave Address Yes No
Baudrate Yes No
Data, Stop and Parity bits Yes No
RS485 Terminating Resistor Yes No
1st Relay active mode Yes Yes
1st Relay active range Yes Yes
2nd Relay active mode Yes Yes
2nd Relay active range Yes Yes
Default Settings Yes No

 

Supported MODBUS functions


01 (0x01) Read Coils Status
Reads status of relays (Off or On). IOMOD HT has 2 relays on addresses 6 and 7 (Only for IOMOD
HT Advanced).

03 (0x03) Read Holding Registers
Reads current configuration of relays. Address 2 – Active Mode for 1st relay ( 0 – disabled, 1 - humidity or 2 - temperature); Address 3 – Lower Active value (minimal value for relays to turn on) for 1st relay; Address 4 – Upper Active value (maximum value for relays to keep turned on. If parameter reaches threshold bigger than this value, relay is turned off) for 1st relay. Address 5 – Active Mode for 2nd relay (humidity or temperature); Address 6 – Lower Active value (minimal value for relays to turn on) for 2nd relay; Address 7 – Upper Active value (maximum value for relays to keep turned on. If parameter reaches threshold bigger than this value, relay is turned off) for 2nd relay.

04 (0x04) Read Input Registers
Reads current Humidity and Temperature status. Address 0 – Humidity; Value is multiplied by 10 to show one decimal place. For example: 23.3 °C will be shown as 233; 50.0 % will be shown as 500 in the Registers.

05 (0x05) Write Single Coil
(Only for IOMOD HT Advanced). Sets single relay On or Off. 1 Relay address – 6th register; 2 relay – 7th register.

06 (0x06) Preset Single Register
Sets single configuration (Only for IOMOD HT Advanced). Address 2 – Active Mode for 1 relay: 0- disabled; 1 - humidity or 2 - temperature; Address 3 – Lower Active value (minimal value for relays to turn on) for 1 relay; Address 4 – Upper Active value (maximum value for relays to keep turned on. If parameter reaches threshold bigger than this value, relay is turned off) for 1 relay. Integer; Address 5 – Active Mode for 2 relay: 0- disabled; 1 - humidity or 2 - temperature; Address 6 – Lower Active value (minimal value for relays to turn on) for 2 relay; Address 7 – Upper Active value (maximum value for relays to keep turned on. If parameter reaches threshold bigger than this value, relay is turned off) for 2 relay.