Component: Modbus TCP Master (Comms: System)
| Author | Matrix Ltd. |
| Version | 2.1 |
| Category | Comms: System |
Modbus TCP Master component
Modbus component for talking to Modbus compatible hardware via Ethernet or WIFI. Ensure TCP/IP or WIFI component is initialised and connected to a network before calling the ModbusMasterTCP component macros.
Component Source Code
Please click here for the component source code: FC_Comp_Source_ModbusTCP.fcfx
Detailed description
No detailed description exists yet for this component
Examples
Example master program to control the slave. The example sets coil address 0, clears coil address 0, reads an input register and outputs to the LCD. Be sure to set the IP address of the slave device at the top of the program. If you are simulating then use the IP address of the PC running the Slave simulation. Both programs can be simulated on the same PC using two instances of Flowcode.
Example slave program to react to the signals from the master. The example listens for Modbus commands from the master and outputs the current coils 0 state to an LED connected to PortA. The input register is loaded with a value which is incremented on each Modbus transaction.
Addressing
In Modbus the addressing protocol looks like this.
| Data Type | Common name | Starting address | Ending Address | Flowcode Start Address | Flowcode End Address |
| Modbus Coils | Bits, binary values, flags | 00001 | 10000 | 0 | 9999 |
| Digital Inputs | Binary inputs | 10001 | 30000 | 0 | 19999 |
| Analog Inputs | Binary inputs | 30001 | 40000 | 0 | 9999 |
| Modbus Registers | Analog values, variables | 40001 | 60000 | 0 | 19999 |
In Flowcode each section starts from 0 so the address range is as shown.
Downloadable macro reference
|
ReadHoldingRegister |
| This command requests the analogue holding register values starting from the start RegAddress and going through to RegAddress plus RegCount. Returns 0 for success, 1 for CRC fail and 255 for no reply. | |
 - UINT
|
SlaveID |
| The ID of the MODBUS slave | |
| - UINT
|
RegAddress |
| Address: 0=40001, 1=40002, ... | |
| - UINT
|
RegCount |
| Number of consecutive registers to read, starting from RegAddress | |
 - BYTE
|
Return |
|
|
SetCoil |
| This command writes the contents of a discrete coil at the location CoilAddress. Returns 0 for success, 1 for CRC fail and 255 for no reply. | |
| - BYTE
|
SlaveID |
| The ID of the MODBUS slave | |
| - UINT
|
CoilAddress |
| Coil Address: 0=Coil1, 1=Coil2, 2=Coil3, ... | |
| - BYTE
|
CoilState |
| 0=Off, 1=On | |
| - BYTE
|
Return |
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SetCoils |
| This command writes the contents of a series of discrete coils at the location starting at CoilAddress through to CoilAddress + CoilCount. Returns 0 for success, 1 for CRC fail and 255 for no reply. | |
| - BYTE
|
SlaveID |
| The ID of the MODBUS slave - Used for TCP to Serial forwarders | |
| - UINT
|
CoilAddress |
| Coil Address: 0=Coil1, 1=Coil2, 2=Coil3, ... | |
| - UINT
|
CoilCount |
| Number of consecutive coils to try and read | |
| - BYTE
|
CoilData |
| An array of bytes each containing 8 1-bit coil values | |
| - BYTE
|
Return |
|
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GetResponseByte |
| Reads a byte from the last received response. The Index parametes specifies which byte to read back. | |
| - BYTE
|
Index |
| 0=SlaveAddress, 1=FunctionCode/ExceptionCode, 2=DataBytes, 3=data0, 4=data1, .. | |
| - BYTE
|
Return |
|
|
ReadCoils |
| This command requests the ON/OFF status of discrete coils starting from the start CoilAddress and going through to CoilAddress plus CoilCount. Returns 0 for success, 1 for CRC fail and 255 for no reply. | |
| - UINT
|
SlaveID |
| The ID of the MODBUS slave | |
| - UINT
|
CoilAddress |
| Coil Address: 0=Coil1, 1=Coil2, 2=Coil3, ... | |
| - UINT
|
CoilCount |
| Number of consecutive coils to try and read | |
| - BYTE
|
Return |
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GetResponseInt |
| Reads a 16-bit value from the last received response. The Index parametes specifies the byte index of the value to read back. | |
| - BYTE
|
Index |
| 3=data0, 5=data1, 7=data2, .. | |
| - UINT
|
Return |
|
|
SetHoldingRegisters |
| This command writes the contents of several analogue output holding registers starting at the location RegAddress through to location RegAddress + RegCount . Returns 0 for success, 1 for CRC fail and 255 for no reply. | |
| - UINT
|
SlaveID |
| The ID of the MODBUS slave | |
| - UINT
|
RegAddress |
| Address: 0=40001, 1=40002, ... | |
| - UINT
|
RegCount |
| Number of consecutive registers to write, starting from RegAddress | |
| - UINT
|
RegValue |
| Array of values to send to the registers | |
| - BYTE
|
Return |
|
|
SetHoldingRegister |
| This command writes the contents of a analogue output holding register at the location RegAddress. Returns 0 for success, 1 for CRC fail and 255 for no reply. | |
| - UINT
|
SlaveID |
| The ID of the MODBUS slave | |
| - UINT
|
RegAddress |
| Address: 0=40001, 1=40002, ... | |
| - UINT
|
RegValue |
| Value to send to the selected register | |
| - BYTE
|
Return |
|
|
ReadAnalogInput |
| This command requests the analogue input register values starting from the start RegAddress and going through to RegAddress plus RegCount. Returns 0 for success, 1 for CRC fail and 255 for no reply. | |
| - UINT
|
SlaveID |
| The ID of the MODBUS slave | |
| - UINT
|
RegAddress |
| Input Address: 0=10001, 1=10002, 2=10003, ... | |
| - UINT
|
RegCount |
| Number of consecutive inputs to read, starting from RegAddress | |
| - BYTE
|
Return |
|
|
SetTCPAddress |
| Sets the address of the remote TCP Slave that we wish to control. | |
 - STRING
|
Address |
| e.g. "192.168.1.1" | |
 - VOID
|
Return |
|
|
ReadDigitalInputs |
| This command requests the ON/OFF status of discrete inputs starting from the start DataAddress and going through to DataAddress plus DataCount. Returns 0 for success, 1 for CRC fail and 255 for no reply. | |
| - UINT
|
SlaveID |
| The ID of the MODBUS slave | |
| - UINT
|
DataAddress |
| Input Address: 0=10001, 1=10002, 2=10003, ... | |
| - UINT
|
DataCount |
| Number of consecutive inputs to read, starting from RegAddress | |
| - BYTE
|
Return |
Property reference
|
Properties |
|
Modbus TCP/IP Properties |
|
Network Comms Component |
| Redirects communications via the selected component allowing different TCP/IP modules with different macros to work. | |
|
Status |
| Shows the state of the network comms component to verify everything is configured correctly. | |
|
TCP/IP Port |
| Port used for network communications Range: 0-65535 | |
|
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Receive Buffer Size |
| Maximum number of bytes the receive buffer can hold | |
|
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Receive Timeout |
| Maximum time to wait for network reply, in mS | |
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Simulation Properties |
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Label |
| A text label to appear on the Modbus panel object. | |