JSON protocol:

Modbus Command Set

Modbus mode configuration

There is an RS485 communication interface respectively at the aerial plug of the controller and the aerial plug of the end interface board of the RealMan robotic arm. The two RS485 ports can be configured to standard ModbusRTU mode through the JSON protocol. Then the peripherals connected to the interface can be read or written through the JSON protocol.

Note: The RS485 port of the controller can be used to control the robotic arm when it is not configured to ModbusRTU mode. These two modes are not compatible with each other. To restore the robotic arm control mode, the ModbusRTU mode of the interface must be closed. After the ModbusRTU mode is closed, the system will automatically switch back to the robotic arm control mode, using the baud rate of 460800BPS, stop bit 1, data bit 8, no parity check.

In addition, the Gen 3 controller also supports ModbusTCP master configuration, allowing users to configure the ModbusTCP master to connect the ModbusTCP slaves of external devices.

Set RS485set_RS485

Set the RS485 port baud rate, but there is no return response. Baud rate options: 9600, 19200, 38400, 115200, and 460800. If the user sets a different value, the controller will default to 460800. After issuing this command, if the Modbus mode is enabled, it will automatically be disabled. The controller will then record the current baud rate and continue to use this baud rate for external communication even after a power cycle.

• Input parameter

Parameter	Type	Description
set_RS485	string	Set the RS485 port baud rate, with a maximum of 460800.

• Code demo

Input

Set the baud rate of the RS485 to 460800.

{"command":"set_RS485","baudrate":460800}

Get the controller RS485 mode (Gen 3)get_controller_RS485_mode

• Input parameter

Parameter	Type	Description
get_controller_RS485_mode	string	Get the controller RS485 mode.

• Output parameter

Parameter	Type	Description
controller_RS485_mode	int	0: RS485 serial communication by default, 1: modbus-RTU master mode, 2: modbus-RTU slave mode.
baudrate	int	Baud rate.
modbus_timeout	int	modbus protocol timeout period in 100 ms, available only in modbus-RTU mode.

• Code demo

Input

Get the controller RS485 mode.

{"command":"get_controller_RS485_mode"}

Output

{
    "command": "get_controller_RS485_mode",
    "controller_RS485_mode": 1,
    "baudrate": 460800,
    "modbus_timeout": 1
}

Get the tool RS485 mode (Gen 3)get_tool_RS485_mode

• Input parameter

Parameter	Type	Description
get_tool_RS485_mode	string	Get the tool RS485 mode.

• Output parameter

Parameter	Type	Description
tool_RS485_mode	int	0: RS485 serial communication by default, 1: modbus-RTU master mode, 2: modbus-RTU slave mode.
baudrate	int	Baud rate.
modbus_timeout	int	modbus protocol timeout period in 100 ms, available only in modbus-RTU mode.

• Code demo

Input

Get the tool RS485 mode.

{"command":"get_tool_RS485_mode"}

Output

{
    "command": "get_tool_RS485_mode",
    "tool_RS485_mode": 0,
    "baudrate": 460800,
    "modbus_timeout": 1
}

Set ModbusRTU mode of communication portset_modbus_mode

Set the ModbusRTU mode of communication port. After the robotic arm is started, this command must be initiated first for any operation on the communication port; otherwise, error information will be returned.

• Input parameter

Parameter	Type	Description
set_modbus_mode	string	Set ModbusRTU mode of communication port.
port	int	Communication port, 0: controller RS485 port as RTU master, 1: end interface board RS485 port as RTU master, 2: controller RS485 port as RTU slave.
baudrate	int	Baud rate, supporting three common baud rates, namely 9600, 115200, and 460800.
timeout	int	Timeout period, in 100 ms. For all read and write commands to the Modbus device, if no response data is returned within the specified timeout period, a timeout error will be returned. The timeout period cannot be set to 0; if set to 0, the robotic arm will take it as 1 for configuration.

• Code demo

Input

{"command":"set_modbus_mode","port":0,"baudrate":115200,"timeout":1}

Output Setting succeeded

{
    "command": "set_modbus_mode",
    "set_state": true
}

Setting failed

{
    "command": "set_modbus_mode",
    "set_state": false
}

Close ModbusRTU mode of communication portclose_modbus_mode

• Input parameter

Parameter	Type	Description
close_modbus_mode	string	Close ModbusRTU mode of communication port.
port	int	Communication port, 0: controller RS485 port as RTU master, 1: end interface board RS485 port as RTU master, 2: controller RS485 port as RTU slave.

• Code demo

Input

{"command":"close_modbus_mode","port":0}

Output Setting succeeded:

{
    "command": "close_modbus_mode",
    "set_state": true
}

Setting failed:

{
    "command": "close_modbus_mode",
    "set_state": false
}

Set to connect to ModbusTCP slave (Gen 3 controller)rm_set_modbustcp_mode()

The controller acts as a ModbusTCP master to connect to external ModbusTCP slave devices.

• Input parameter

Parameter	Type	Description
set_modbustcp_mode	string	Connect to ModbusTCP slave.
ip	string	Slave IP address.
port	int	Communication port number.
timeout	int	Timeout period, in ms.

• Code demo

Input

{"command":"set_modbustcp_mode","ip":"192.168.1.120","port":502,"timeout":2000}

Output Connection succeeded:

{
    "command": "set_modbustcp_mode",
    "set_state": true
}

Connection failed:

{
    "command": "set_modbustcp_mode",
    "set_state": false
}

Close ModbusTCP slave (Gen 3 controller)close_modbustcp_mode

• Input parameter

Parameter	Type	Description
close_modbustcp_mode	string	Disconnect to ModbusTCP slave.

• Code demo

Input

{"command":"close_modbustcp_mode"}

Output Success:

{
    "command": "close_modbustcp_mode",
    "set_state": true
}

Fail:

{
    "command": "close_modbustcp_mode",
    "set_state": false
}

Modbus protocol command

Read coilsread_coils

• Input parameter

Parameter	Type	Description
read_coils	string	Read coils.
port	int	Communication port, 0: controller RS485 port, 1: end interface board RS485 port, 3: controller ModbusTCP port for connecting to external slave devices.
address	int	Coil starting address.
num	int	Number of coils to read. This command can read up to 8 coils once, that is, the returned data will not be longer than one byte.
device	int	Peripheral device address.

• Code demo

Input

{"command":"read_coils","port":0,"address":10,"num":2,"device":2}

Output Reading succeeded, returning coil state, data type: int8.

{
    "command": "read_coils",
    "data": 8
}

Reading failed, no data received within the timeout period.

{
    "command": "read_coils",
    "read_state": false
}

Read multiple coilsread_multiple_coils

• Input parameter

Parameter	Type	Description
read_multiple_coils	string	Read multiple coils.
port	int	Communication port, 0: controller RS485 port, 1: end interface board RS485 port, 3: controller ModbusTCP port for connecting to external slave devices.
address	int	Coil starting address.
num	int	8 ≤ num ≤ 120 represents the number of wire coils to be read. This command supports reading up to 120 coils at a time, which is equivalent to 15 bytes.
device	int	Peripheral Device Address.

• Code demo

Input

{"command":"read_multiple_coils","port":0,"address":0,"num":24,"device":2}

Output Reading succeeded, returning coil state, data type: int8.

{
    "command": "read_multiple_coils",
    "data": [
        1,
        2,
        3
    ]
}

Reading failed, no data received within the timeout period.

{
    "command": "read_multiple_coils",
    "read_state": false
}

Write single coil datawrite_single_coil

• Input parameter

Parameter	Type	Description
write_single_coil	string	Write single coil data.
port	int	Communication port, 0: controller RS485 port, 1: end interface board RS485 port, 3: controller ModbusTCP port for connecting to external slave devices.
address	int	Coil starting address.
data	int	Data to be written to the coil, data type: int16.
device	int	Peripheral device address.

• Code demo

Input

{"command":"write_single_coil","port":0,"address":10,"data":1,"device":2}

Output

Writing succeeded.

{
    "command": "write_single_coil",
    "write_state": true
}

Writing failed, no data received within the timeout period or an error occurred in the command content.

{
    "command": "write_single_coil",
    "write_state": false
}

Write multi-coil datawrite_coils

• Input parameter

Parameter	Type	Description
write_coils	string	Write multi-coil data.
port	int	Communication port, 0: controller RS485 port, 1: end interface board RS485 port, 3: controller ModbusTCP port for connecting to external slave devices.
address	int	Coil starting address.
num	int	Number of coils to write, with the quantity written each time not exceeding 160.
data	int	The data group to be written to the coils, type: byte. If the number of coils is not greater than 8, the data to be written is one byte; otherwise, it is an array of multiple data.
device	int	Peripheral device address.

• Code demo

Input

{"command":"write_coils","port":0,"address":10,"num":16,"data":[15,20],"device":2}

Output Writing succeeded.

{
    "command": "write_coils",
    "write_state": true
}

Writing failed, no data received within the timeout period or an error occurred in the command content.

{
    "command": "write_coils",
    "write_state": false
}

Read discrete inputsread_input_status

• Input parameter

Parameter	Type	Description
read_input_status	string	Read discrete inputs.
port	int	Communication port, 0: controller RS485 port, 1: end interface board RS485 port, 3: controller ModbusTCP port for connecting to external slave devices.
address	int	Coil starting address.
num	int	Number of data to read. This command can read up to 8 discrete datas once, that is, the returned data will not be longer than one byte.
device	int	Peripheral device address.

• Code demo

Input

{
    "command": "read_input_status",
    "port": 0,
    "address": 10,
    "num": 2,
    "device": 2
}

Output Reading succeeded, returning discrete magnitude, data type: int8.

{
    "command": "read_input_status",
    "data": 8
}

Reading failed, no data received within the timeout period.

{
    "command": "read_input_status",
    "read_state": false
}

Read holding registerread_holding_registers

• Input parameter

Parameter	Type	Description
read_holding_registers	string	Read holding register.
port	int	Communication port, 0: controller RS485 port, 1: end interface board RS485 port, 3: controller ModbusTCP port for connecting to external slave devices.
address	int	Data starting address, this command can only read one register at a time, which is 2 bytes of data, and cannot read data from multiple registers at once.
device	int	Peripheral device address.

• Code demo

Input

{"command":"read_holding_registers","port":0,"address":10,"device":2}

Output Reading succeeded, returning register data, data type: int16.

{
    "command": "read_holding_registers",
    "data": 16
}

Reading failed, no data received within the timeout period.

{
    "command": "read_holding_registers",
    "read_state": false
}

Write single registerwrite_single_register

• Input parameter

Parameter	Type	Description
write_single_register	string	Write single register.
port	int	Communication port, 0: controller RS485 port, 1: end interface board RS485 port, 3: controller ModbusTCP port for connecting to external slave devices.
address	int	Register starting address.
data	int	Data to be written to the Register, data type: int16.
device	int	Peripheral device address.

• Code demo

Input

{"command":"write_single_register","port":0,"address":10,"data":1000,"device":2}

Output Writing succeeded.

{
    "command": "write_single_register",
    "write_state": true
}

Writing failed, no data received within the timeout period or an error occurred in the command content.

{
    "command": "write_single_register",
    "write_state": false
}

Write multiple registerswrite_registers

• Input parameter

Parameter	Type	Description
write_registers	string	Write multiple registers.
port	int	Communication port, 0: controller RS485 port, 1: end interface board RS485 port, 3: controller ModbusTCP port for connecting to external slave devices.
address	int	Coil starting address.
num	int	Number of registers to write. This command can write up to 10 registers once.
data	int	Data to be written to the coil, data type: int16.
device	int	Peripheral device address.

• Code demo

Input

{"command":"write_registers","port":0,"address":10,"num":2,"data":[15,20,25,30],"device":2}

Output Writing succeeded.

{
    "command": "write_registers",
    "write_state": true
}

Writing failed, no data received within the timeout period or an error occurred in the command content.

{
    "command": "write_registers",
    "write_state": false
}

Read multiple holding registersread_multiple_holding_registers

• Input parameter

Parameter	Type	Description
read_multiple_holding_registers	string	Read multiple holding registers.
port	int	Communication port, 0: controller RS485 port, 1: end interface board RS485 port, 3: controller ModbusTCP port for connecting to external slave devices.
address	int	Registers starting address.
num	int	The number of registers to read is 2 < num ≤ 13. This command can read up to 12 registers once, that is, 24 bytes.
device	int	Peripheral device address.

• Code demo

Input

{"command":"read_multiple_holding_registers","port":0,"address":0,"num":5,"device":2}

Output Reading succeeded, returning register data, data type: int8.

{
    "command": "read_multiple_holding_registers",
    "data": [
        1,
        2,
        3,
        4,
        5,
        6,
        7,
        8,
        9,
        10
    ]
}

Reading failed, no data received within the timeout period.

{
    "command": "read_multiple_holding_registers",
    "read_state": false
}

Read input registerread_input_registers

• Input parameter

Parameter	Type	Description
read_input_registers	string	Read input register.
port	int	Communication port, 0: controller RS485 port, 1: end interface board RS485 port, 3: controller ModbusTCP port for connecting to external slave devices.
address	int	Coil starting address.
device	int	Peripheral device address.

• Code demo

Input

{"command":"read_input_registers","port":0,"address":10,"device":2}

Output Reading succeeded, returning register data, data type: int16.

{
    "command": "read_input_registers",
    "data": 8
}

Reading failed, no data received within the timeout period.

{
    "command": "read_input_registers",
    "read_state": false
}

Read multiple input registersread_multiple_input_registers

• Input parameter

Parameter	Type	Description
read_multiple_input_registers	string	Read multiple input registers.
port	int	Communication port, 0: controller RS485 port, 1: end interface board RS485 port, 3: controller ModbusTCP port for connecting to external slave devices.
address	int	Coil starting address.
num	int	The number of registers to read is 2 < num < 13. This command can read up to 12 registers once, that is, 24 bytes.
device	int	Peripheral device address.

• Code demo

Input

{"command":"read_multiple_input_registers","port":0,"address":0,"num":5,"device":2}

Output Reading succeeded, returning register data, data type: int8.

{
    "command": "read_multiple_input_registers",
    "data": [
        1,
        2,
        3,
        4,
        5,
        6,
        7,
        8,
        9,
        10
    ]
}

Reading failed, no data received within the timeout period.

{
    "command": "read_multiple_input_registers",
    "read_state": false
}