Modbus/TCP
ModbusTCP parameters follow these URL schemas:
modbus://<IP>/<Unit ID>/<Function Code>/<Value Type>/<ID>
modbus://<IP>/<Unit ID>/<Function Code>/<Value Type>/<ID>/<bit>
IP
IPv4 IP address of the Modbus device, you are trying to connect to. This must be on the same network as the LAN side of the INDAQ interface.
Unit ID
The address/location of the Modbus device you are trying to communicate with. This is typically 1 for most devices.
Function Code
Select which function code to use when communicating with the Modbus device.
| Function Name | Function Code | Description |
|---|---|---|
| Read Coil Status | 2 | Function used to read boolean values from the Modbus device. |
| Read Holding Registers | 3 | Function used to read from a holding registers, which are 16-bit registers that can be read and written to.1 |
| Read Input Registers | 4 | Function used to read from input registers, which are 16-bit registers that can only be read from. |
Value Type
The value type of the register you are trying to read from the Modbus device. This is used to determine how to interpret the raw value from the device. Since Modbus operates on 16 bit values, INDAQ will automatically pull as many registers as needed to satisfy the value type.
| Value Type Name | Value Type Id | Description |
|---|---|---|
| single bit | u1 | A single bit value. |
| signed 16 bit integer | i16 | A 16-bit signed integer. |
| unsigned 16 bit integer | u16 | A 16-bit unsigned integer. |
| signed 32 bit integer | i32 | A 32-bit signed integer. |
| unsigned 32 bit integer | u32 | A 32-bit unsigned integer. |
| 32 bit floating point | f32 | A 32-bit floating point number. |
ID
The register id to read from the Modbus device. This is a 16 bit unsigned value, ranging from 1 to 65536.
Bit
When selecing the single bit value type, you can specify the bit to read from the register. This is a 0 based revsered index, which 0 indicating the least significant bit.
Footnotes
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INDAQ will not write to this register. ↩