API Templates

In order to set you up quickly, there are two API templates, which allow to create a Modbus client from a simple API definition. The API definition is assumed to be provided in terms of a dictionary, which contains a meaningful key (such as the numeric message ID or a string) as key and a Payload object as value.

Default API Template

class modbusclient.api_wrapper.ApiWrapper(api={}, host='', port=502, timeout=None, connect=False, unit=255)

Default API implementation to quickly

Parameters:

• api (dict) – Dictionary containing the API definition. Should contain a string with desired method name as key and a Payload object as value.
• host (str) – IP address of the server. Passed verbatim to Client
• port (int) – Port to connect to at the server. Passed verbatim to Client
• timeout (int) – Client timeout. Passed verbatim to Client
• connect (bool) – Connect to the client. Defaults to False. Passed verbatim to Client

unit

int – Modbus unit ID: Defaults to NO_UNIT.

__enter__()

Context Manager support

Connects to the server if not already connected.

__exit__(type, value, traceback)

Context Manager support

Logs out and disconnects from the server.

connect(**kwargs)

Connect this client to a host

Parameters:

• address (string) – IP Adress of the host
• port (int) – Port to use. Defaults to 502
• timeout (float) – Timeout in seconds. If not set, it will be set to the default timeout.

disconnect()

Disconnect this client

If this client is connected, the socket will be shutdown and then closed. If the client is not connected, calling this method has no effect.

get(message)

Get value of a single message

Parameters:message (Payload or str) – Message to read from remote device. If this is not a Payload instance, the api dictionary will be used with message as key to lookup the payload. Returns:Value of message Return type:value

is_connected()

Check if this client is connected to a server

Returns:True if and only if this client is connected to a server Return type:bool

is_logged_in()

Check if this client is currently logged in

Intended to be implemented by derived class, if applicable

Returns:False. Return type:bool

load(settings)

Load settings from dictionary

Parameters:settings (dict) – Dictionary with settings as returned by save() Returns:Successfully modified settings Return type:list

logout()

Log out client

This is a stub. Intended to be implemented by derived classes.

save(selection=None)

Save current settings into dictionary

Parameters:selection (iterable) – Iterable of messages (API keys) to save. If None, all messages of the current API are backed up. Returns:Dictionary containing API message key and setting as value Return type:dict

set(message, value)

Set value of a single message

Parameters:

• message (Payload) – Message to write to remote device. If this is not a Payload instance, the api dictionary will be used with message as key to lookup the payload.
• value (object) – Value to set for this message.

Returns:

Value of message

Return type:

value

Asynchronous API Template

class modbusclient.asyncio.api_wrapper.ApiWrapper(api={}, host='', port=502, timeout=None, max_transactions=3, unit=255)

Asynchronous API implementation

Parameters:

• api (dict) – Dictionary containing the API definition. Should contain a string with desired method name as key and a Payload object as value.
• host (str) – IP address of the server. Passed verbatim to Client
• port (int) – Port to connect to at the server. Passed verbatim to Client
• timeout (int) – Client timeout. Passed verbatim to Client
• max_transactions (int) – Maximum number of parallel transactions. Passed verbatim to Client.
• unit (int) – Modbus unit ID to use. Defaults to NO_UNIT.

unit

int – Modbus unit ID: Defaults to NO_UNIT.

__aenter__()

Context Manager support

Connects to the server if not already connected.

__aexit__(type, value, traceback)

Context Manager support

Logs out and disconnects from the server.

connect(**kwargs)

Connect this client to a host

Parameters:

• address (string) – IP Adress of the host
• port (int) – Port to use. Defaults to 502
• timeout (float) – Timeout in seconds. If not set, it will be set to the default timeout.

disconnect()

Disconnect this client

If this client is connected, the socket will be shutdown and then closed. If the client is not connected, calling this method has no effect.

get(message)

Get value of a single message

Parameters:message (Payload or str) – Message to read from remote device. If this is not a Payload instance, the api dictionary will be used with message as key to lookup the payload. Returns:Value of message Return type:value

is_connected()

Check if this client is connected to a server

Returns:True if and only if this client is connected to a server Return type:bool

is_logged_in()

Check if this client is currently logged in

Intended to be implemented by derived class, if applicable

Returns:False. Return type:bool

load(settings)

Load settings from dictionary

Parameters:settings (dict) – Dictionary with settings as returned by save() Returns:Successfully modified settings Return type:list

logout()

Log out client

This is a stub. Intended to be implemented by derived classes.

save(selection=None)

Save current settings into dictionary

Parameters:selection (iterable) – Iterable of messages (API keys) to save. If None, all messages of the current API are backed up. Returns:Dictionary containing API message key and setting as value Return type:dict

set(message, value)

Set value of a single message

Parameters:

• message (Payload or str) – Message to write to remote device. If this is not a Payload instance, the api dictionary will be used with message as key to lookup the payload.
• value (object) – Value to set for this message.

Returns:

Value of message

Return type:

value