Component: Modbus Slave (Comms: System)
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(Redirected from Component: ID 687f8ad4 59f2 4079 bb84 7713dcb57a13)
Jump to navigationJump to search| Author | Matrix Ltd. |
| Version | 2.0 |
| Category | Comms: System |
Contents
Modbus Slave component
Modbus component for creating Modbus compatible slave hardware via RS232 or RS485.
Component Source Code
Please click here to download the component source project: FC_Comp_Source_ModbusSlave.fcfx
Please click here to view the component source code (Beta): FC_Comp_Source_ModbusSlave.fcfx
Detailed description
No detailed description exists yet for this component
Examples
Example master program to control the slave. The example reads the 8 switches connected to PortD. If the switch values change then the new value is send to the slave.
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 0-7 state to eight LEDs connected to PortD.
Master and Slave example using vNet
Example of communicating using Modbus Master and Slave using two instances of Flowcode and the vNet injector component.
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.
Macro reference
ChangeBaud
|
ChangeBaud |
| Changes the UART Baud rate. 1 = 1200 / 2 = 2400 / 3 = 4800 / 4 = 9600 / 5 = 19200 / 6 = 31250 7 = 38400 / 8 = 57600 / 9 = 115200 | |
 - BYTE
|
Baud |
| The new baud rate (0=1200, 9=115200) | |
 - VOID
|
Return |
ChangeFrameType
|
|
ChangeFrameType |
| Default frame type is the type set in the component properties. | |
| - BYTE
|
Type |
| 0 = Modbus RTU / 1 = Modbus ASCII | |
| - VOID
|
Return |
CheckForIncoming
|
|
CheckForIncoming |
| Checks for an incoming message and if the data address is within range then also automatically replies with the correct reply. Returns 0 if no comms received, 1 for a succesful transaction, 255 for an error. | |
| - BYTE
|
Return |
GetLastIncoming
|
|
GetLastIncoming |
| Gets a value from the last incoming command. Index 0 = 0 Read / 1 Write Index 1 = 0 Coils / 1 DigInput / 2 AnInput / 3 Register Index 2 = Address Index 3 = Number | |
| - BYTE
|
Index |
| Range: 0-3 | |
 - UINT
|
Return |
Initialise
|
|
Initialise |
| Starts up the UART to allow communications and initialises the states of the various Modbus Coils, Inputs and Registers to 0. | |
| - VOID
|
Return |
ReadAnalogInput
|
|
ReadAnalogInput |
| Reads the value of a single analogue input. | |
| - UINT
|
Address |
| Coil Address | |
| - UINT
|
Return |
ReadCoils
|
|
ReadCoils |
| Reads the state of up to eight digital coils. Can pack a max of 8-bits together in a single operation | |
| - UINT
|
StartAddress |
| Coil Address Range 0 to (NumCoils - 1) | |
| - BYTE
|
AddressCount |
| Range 1-8 | |
| - BYTE
|
Return |
ReadDigitalInputs
|
|
ReadDigitalInputs |
| Reads the state of up to eight digital inputs. Can pack a max of 8-bits together in a single operation | |
| - UINT
|
StartAddress |
| Coil Address Range 0 to (NumCoils - 1) | |
| - BYTE
|
AddressCount |
| Range 1-8 | |
| - BYTE
|
Return |
ReadHoldingRegister
|
|
ReadHoldingRegister |
| Reads the value of a single holding register. | |
| - UINT
|
Address |
| Coil Address | |
| - UINT
|
Return |
SetAnalogInput
|
|
SetAnalogInput |
| Sets the state of a single analogue input. | |
| - UINT
|
Address |
| Coil Address | |
| - UINT
|
Value |
| Analogue Value range 0 - 65535 | |
| - VOID
|
Return |
SetBaudRate
|
|
SetBaudRate |
| Allows the Baud Rate to be controlled dynamically overriding the default rate specified by the Baud component property. | |
| - BYTE
|
Rate |
| 0=1200, 1=2400, 2=4800, 3=9600, 4=19200, 5=38400, 6=57600, 7=115200 | |
| - VOID
|
Return |
SetCoil
|
|
SetCoil |
| Sets the state of a single digital coil. | |
| - UINT
|
Address |
| Coil Address | |
| - BYTE
|
State |
| 0=off, 1=on | |
| - VOID
|
Return |
SetDigitalInput
|
|
SetDigitalInput |
| Sets the state of a single digital input. | |
| - UINT
|
Address |
| Coil Address | |
| - BYTE
|
State |
| 0=off, 1=on | |
| - VOID
|
Return |
SetHoldingRegister
|
|
SetHoldingRegister |
| Sets the state of a single holding register. | |
| - UINT
|
Address |
| Coil Address | |
| - UINT
|
Value |
| Analogue Value range 0 - 65535 | |
| - VOID
|
Return |
SetSlaveAddress
|
|
SetSlaveAddress |
| Allows the slave address to be overridden from the default slave address specified in the component property. The number of bytes used for the address is fixed by the Slave ID Bytes property to save on RAM usage. | |
| - UINT
|
SlaveAddress |
| - VOID
|
Return |
Property reference
|
Properties |
|
UART Properties |
|
Channel |
| UART Channel selector Software channels are bit banged using generic I/O pins but are not as reliable as hardware channels. Hardware channels use the selected peripheral on-board the target microcontroller. | |
|
TX |
| Pin to be used for Transmit data | |
|
|
RX |
| Pin to be used for Receive data | |
|
|
Baud Options |
| Baud rate option selector | |
|
Baud Rate |
|
|
Bus |
| Specifies the bus mode being used, RS232 allows you to connect a single master node to a single slave node. RS485 allows you to connect a single master node to multiple slave nodes. | |
|
Timeout |
| Timeout in milliseconds used to dictate the maximum time to wait in milliseconds between bytes in a packet. Range: 1 - 255 | |
|
|
Modbus Properties |
|
|
Frame Type |
| Switches between RTU and ASCII forms of Modbus | |
|
|
Receive Buffer Size |
| Maximum number of bytes the receive buffer can hold | |
|
|
Slave ID Bytes |
| Number of bytes used when passing a slave ID, usually 1 but sometimes 2 | |
|
|
Slave Address |
|
|
Reply Delay |
| Delay in micro seconds to wait before transmitting a reply | |
|
Maintain Stats |
| Controls if the last command from the master is logged allowing for easier value updates. No - Do not log commands Yes - Commands are logged and available via the GetLastIncoming macro | |
|
|
Simulation Properties |
|
Label |
| A text label to appear on the Modbus panel object. | |
|
|
Scope Traces |
| Selects if the scope traces are automatically added to the data recorder window or not. Simulation - draws an approximation of the UART data onto the scope trace. ICT - sets up the scope trace for incoming data and adds UART packet decoding at the correct BAUD. | |
|
|
Console Data |
| Selects if the console data is automatically generated or not | |
|
|
Console Columns |
| Number of characters that can be displayed on a single line of the console. | |
|
|
Data Source |
| Simulation data source used to allow the component to connect to various remote devices Nothing - Simulation data is ignored COM port - Routes the communication data to and from a physical or virtual COM port API - Routes the communication data via a data API component on the Panel. | |
|
|
API |
| Selects which API component to route the communication data via. Add API components to the panel before they will be available in this list. API components are available from the Comms component category. | |
|
|
Modbus Coils - Single bit values |
|
|
Starting Address |
| Start address of the Modbus coils. Referenced from 0. For example Slave 1 might have 100 coils addressed 0-99 Start Address = 0 Slave 2 might have 100 coils addressed 100-199 Start Address = 100 | |
|
|
Number of Addresses |
| Specifies how many Coils are available on the slave. Each address consumes a single bit of RAM, 8 Addresses are packed together into a single RAM Byte. | |
|
|
Digital Inputs - Single bit values |
|
|
Starting Address |
| Start address of the Modbus digital inputs. Referenced from 0. For example Slave 1 might have 100 inputs addressed 0-99 Start Address = 0 Slave 2 might have 100 inputs addressed 100-199 Start Address = 100 | |
|
|
Number of Addresses |
| Specifies how many Digital Inputs are available on the slave. Each address consumes a single bit of RAM, 8 Addresses are packed together into a single RAM Byte. | |
|
|
Analog Inputs - 16-bit values |
|
|
Starting Address |
| Start address of the Modbus analogue inputs. Referenced from 0. For example Slave 1 might have 100 inputs addressed 0-99 Start Address = 0 Slave 2 might have 100 inputs addressed 100-199 Start Address = 100 | |
|
|
Number of Addresses |
| Specifies how many 16-bit analogue inputs are available on the slave. Each address consumes two RAM Bytes. | |
|
|
Holding Registers - 16-bit values |
|
|
Starting Address |
| Start address of the Modbus registers. Referenced from 0. For example Slave 1 might have 100 registers addressed 0-99 Start Address = 0 Slave 2 might have 100 registers addressed 100-199 Start Address = 100 | |
|
|
Number of Addresses |
| Specifies how many 16-bit holding registers are available on the slave. Each address consumes two RAM Bytes. | |
