Rs485 Modbus Interface; Function Codes; Bytes And Words; Input Registers Address Map - ION TITAN 2 User Manual

RS485 Modbus Interface

The Titan 2 Modbus interface uses either Serial ASCII format Modbus or RTU, at:
•
38400 baud 8 data bits, no parity, 2 stop bits.

Function Codes

Titan 2 supports these function codes:
0x03 – Read Holding Registers
•
• 0x04 – Read Input Registers
• 0x10 – Write Multiple Registers
The address map for Read Holding Registers and Write Multiple Registers is the same – but not all addresses are
writeable.

Bytes and Words

Modbus registers are generally 16 bits in length. For example if you send the command to Read Input Registers with a
register quantity of 1 you will receive 2 bytes (1 word) of data. In the tables of addresses, we specify the length in bytes.
This is the number of bytes of data associated with the read/write at that address.
Thus your Modbus request will be for half that number of registers.

Input Registers Address Map

Use the function code 0x04 to Read Input Registers in the address range given in the table. If you read more than the
number of bytes indicated for the length at each address, any bytes beyond the length are undefined.
For example, if you read 32 bytes at address 1000, only the first 16 bytes returned are valid.
Address Data
(hex) Length
(bytes)
0 60
P eering Gas Sensing Technology.
ion
Content
Returns block of 15 integers for latest result
Integer Meaning
1 Benzene value in ppm x 10
2 Sensor temperature in degC x 100
3 Ambient temperature in degC x 10
4 Flow in ml/min x 100
5 PS1 diagnostic
6 PS2 diagnostic
7 PS3 diagnostic
8 Slope diagnostic
9 Flags
10 Sensor fence signal
11 Raw signal
12 STEL value
13 Pump drive signal
14 Pump drive volts
15 Fault record
TITAN 2 Instrument User Manual V1.0
Page 18 of 66 ionscience.com