Sends a Modbus message to write to floating-point holding registers to a server unit. Write floating-point holding registers (FC16) ParametersĠ – If the function was successful int modbus_write_holding_regs_fp ( const int iface, const uint8_t unit_id, const uint16_t start_addr, float * const reg_buf, const uint16_t num_regs ) ¶ Sends a Modbus message to read the value of floating-point holding registers from a server unit. Read floating-point holding registers (FC03) Num_regs – Quantity of registers to writeĠ – If the function was successful int modbus_read_holding_regs_fp ( const int iface, const uint8_t unit_id, const uint16_t start_addr, float * const reg_buf, const uint16_t num_regs ) ¶ Note that the array containing the register values must be greater than or equal to ‘num_regs’ Reg_buf – Is a pointer to an array containing the value of the holding registers to write. Sends a Modbus message to write to integer holding registers to a server unit. Note that the array that will be receiving the coil values must be greater than or equal to: (num_coils - 1) / 8 + 1Ġ – If the function was successful int modbus_write_holding_regs ( const int iface, const uint8_t unit_id, const uint16_t start_addr, uint16_t * const reg_buf, const uint16_t num_regs ) ¶ ParametersĬoil_tbl – Pointer to an array of bytes containing the value of the coils to write. Sends a Modbus message to write to coils on a server unit. ParametersĠ – If the function was successful int modbus_write_coils ( const int iface, const uint8_t unit_id, const uint16_t start_addr, uint8_t * const coil_tbl, const uint16_t num_coils ) ¶ Sends a Modbus message to perform a diagnostic function of a server unit. Reg_val – Desired value of the holding registerĠ – If the function was successful int modbus_request_diagnostic ( const int iface, const uint8_t unit_id, const uint16_t sfunc, const uint16_t data, uint16_t * const data_out ) ¶ Sends a Modbus message to write the value of single holding register to a server unit. ParametersĬoil_state – Is the desired state of the coilĠ – If the function was successful int modbus_write_holding_reg ( const int iface, const uint8_t unit_id, const uint16_t start_addr, const uint16_t reg_val ) ¶ Sends a Modbus message to write the value of single coil to a server. The array pointed to by ‘reg_buf’ needs to be able to hold at least ‘num_regs’ entries.Ġ – If the function was successful int modbus_write_coil ( const int iface, const uint8_t unit_id, const uint16_t coil_addr, const bool coil_state ) ¶ Reg_buf – Is a pointer to an array that will receive the current value of the holding registers from the server. Sends a Modbus message to read the value of input registers from a server. The array pointed to by ‘reg_buf’ needs to be able to hold at least ‘num_regs’ entries.Ġ – If the function was successful int modbus_read_input_regs ( const int iface, const uint8_t unit_id, const uint16_t start_addr, uint16_t * const reg_buf, const uint16_t num_regs ) ¶ Reg_buf – Is a pointer to an array that will receive the current values of the holding registers from the server. Sends a Modbus message to read the value of holding registers from a server. Num_di – Quantity of discrete inputs to readĠ – If the function was successful int modbus_read_holding_regs ( const int iface, const uint8_t unit_id, const uint16_t start_addr, uint16_t * const reg_buf, const uint16_t num_regs ) ¶ Note that the array that will be receiving the discrete input values must be greater than or equal to: (num_di - 1) / 8 + 1 Modbus TCP to serial line gateway sample is an example how to build a TCP to serial line Modbus TCP Server Sample is a simple Modbus TCP server. The possibility to try out RTU server and RTU client implementation with Modbus RTU Server Sample and Modbus RTU Client Sample give More information about Modbus and Modbus RTU can be found on the website Zephyr RTOS implementation supports both client and server roles. Services requested by the client are specified by function codes (FCxx),Īnd can be found in the specification or documentation of the API below. Server devices themselves are passive and must not send Only one client may be present on the bus. Modbus communication is based on client/server model. To realize TCP support according to the application’s needs. TCP support is not implemented directly, but there are helper functions With different physical interfaces, like RS485 or RS232. Supports communication over serial line and may be used The protocol is specifiedįor different types of networks or buses. Modbus is an industrial messaging protocol.
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