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Configuration
Function code
Name
Description
0x01
Coils
A coil is considered as a discrete output and is either a
zero or one (1 bit)
0x02
Discrete Inputs
The is a single input and is either a zero or one (1 bit)
0x03
Holding Registers
A holding register is 16 bit and can be interpreted as
different data types
0x04
Input Registers
An input register can be considered as a bit field of inputs
(16 bits per register)
Table 12 – Supported reading function codes when the iRIS is a Master
The most versatile of the register types is the Holding register. Each is 16 bits in length and several can be can be
combined to make lager dater types.
Data Type Label
Number of registers used
Description
U_INT16
1
The unsigned integer type represents whole numbers
between 0 and 65,535
S_INT16
1
The signed integer type represents whole numbers
between -32,768 and 32,768
ON_OFF
1
Single bit either zero or one.
U_INT32
2
The unsigned integer type represents whole numbers
between 0 and 4,294,967,295
S_INT32
2
The signed integer type represents whole numbers
between -2,147,483,648 and 2,147,483,647
FLOAT
2
The floating point data type is in an IEEE754 single
precision format.
Table 13 – Data types supported by the iRIS
When the iRIS acts as a slave the Master can either read the current and last logged values for each of the sensor (1 -50).
These are held in holding registers and represented as floating point data types (using two registers). The register address
for each address are listed in Table
Modbus holding register map for iRIS sensors
.
Also, the Master can write data to the iRIS as a data source. This is done by performing either a single or multiple holding
register write. The starting holding register location for this is at 40201. The location of each of the registers that follow
are dynamically allocated based on the user created data types.
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