Built-in GET/SET RPC Methods

The built-in GET and SET methods read and write any node by its node ID, for example the one in the value of a telemetry entry in the connector configuration.

For example, given a timeseries entry:

{
  "timeseries": [
    {
      "key": "temperature",
      "type": "identifier",
      "value": "${ns=3;i=1001}"
    }
  ]
}

Read the current value of a node by its OPC-UA node ID:

get ns=3;i=1001;

Response:

{"result": {"value": 25.34}}

Write a numeric value to a node:

set ns=3;i=1001; 23

Write a string value to an attribute node (e.g. set model to T3000):

set ns=3;i=1008; T3000

Response:

{"result": {"value": "T3000"}}

Read the value of a Modbus slave register:

get type=<type>;functionCode=<functionCode>;objectsCount=<objectsCount>;address=<address>;

Example — read a 16-bit integer from register 1 (outdoor temperature):

get type=16int;functionCode=3;objectsCount=1;address=1;

Response:

{"result": 13}

Write a value to a Modbus slave register:

set type=<type>;functionCode=<functionCode>;objectsCount=<objectsCount>;address=<address>;value=<value>;

Example — write 80 to register 2 (room light level):

set type=16int;functionCode=6;objectsCount=1;address=2;value=80;

Response:

{"result": "80"}

Verify by reading the register back:

get type=16int;functionCode=3;objectsCount=1;address=2;

Response:

{"result": 80}

Subscribe to a response topic and publish a request to read a value:

get requestTopicExpression=<requestTopic>;responseTopicExpression=<responseTopic>;value=<value>;

Example — read the room light level from data/get_light_level, receiving the response on data/response:

get requestTopicExpression=data/get_light_level;responseTopicExpression=data/response;value=light_level;

Publish a message to an MQTT topic:

set requestTopicExpression=<requestTopic>;value=<value>;

Example — set the room light level to 80:

set requestTopicExpression=data/set_light_level;value=80;

Verify by sending a GET request:

get requestTopicExpression=data/get_light_level;responseTopicExpression=data/response;value=light_level;

Read a property value from a BACnet device:

get objectType=<objectType>;objectId=<objectId>;propertyId=<propertyId>;

Example — read the current room light level (analogValue, object 1, presentValue):

get objectType=analogValue;objectId=1;propertyId=presentValue;

Response:

{"result": "30.5"}

Write a property value to a BACnet device:

set objectType=<objectType>;objectId=<objectId>;propertyId=<propertyId>;priority=<priority>;value=<value>;

Example — set the room light level to 31.5:

set objectType=analogValue;objectId=1;propertyId=presentValue;value=31.5;

Response:

{"result": "31.5"}

Verify with GET:

get objectType=analogValue;objectId=1;propertyId=presentValue;

Response:

{"result": "31.5"}

Reserved GET/SET RPC methods work differently depending on the PLC family. S7 PLCs support both data and tag addressing, while Siemens Logo! PLCs are addressed using vmAddress.

• PLC
• Logo!

GET

Section titled “GET”

data type addressing

Section titled “data type addressing”

Read a value from an S7 PLC using data type addressing:

get type=data;dbNumber=<dbNumber>;start=<start>;dataType=<dataType>;size=<size>;bit=<bit>;

Parameter	Description
dbNumber	DB number for S7 PLCs
start	Start address for S7 PLCs
dataType	Data type of the value to read
size	Size of the parameter in bytes for S7 PLCs
bit	Bit number for S7 PLCs. Only for boolean values

Example — read a boolean status flag from DB1, byte 0, bit 1:

get type=data;dbNumber=1;start=0;dataType=bool;size=1;bit=1;

Response:

{"result": true}

tag type addressing

Section titled “tag type addressing”

Read a value from an S7 PLC using tag type addressing:

get type=tag;tag=<tag>;

Parameter	Description
tag	Tag address for S7 PLCs

Example:

get type=tag;tag=DB1.DBD104:REAL;

SET

Section titled “SET”

data type addressing

Section titled “data type addressing”

Write a value to an S7 PLC using data type addressing:

set type=data;dbNumber=<dbNumber>;start=<start>;dataType=<dataType>;size=<size>;bit=<bit>;value=<value>;

Parameter	Description
dbNumber	DB number for S7 PLCs
start	Start address for S7 PLCs
dataType	Data type of the value to write
size	Size of the parameter in bytes for S7 PLCs (optional)
bit	Bit number for S7 PLCs. Only for boolean values
value	Value that will be written to the device

Example — set a boolean status flag at DB1, byte 0, bit 1 to false:

set type=data;dbNumber=1;start=0;dataType=bool;size=1;bit=1;value=false;

Response:

{"result":"Successfully wrote value bytearray(b'\\x00') to device Demo Device for RPC method set"}

tag type addressing

Section titled “tag type addressing”

Write a value to an S7 PLC using tag type addressing:

set type=tag;tag=<tag>;value=<value>;

Parameter	Description
tag	Tag address for S7 PLCs
value	Value that will be written to the device

Example:

set type=tag;tag=DB1.DBD104:REAL;value=12345;

Send a GET request to a REST endpoint:

get requestUrlExpression=<url>;

Example — read the room light level from http://127.0.0.1:8000/light-level:

get requestUrlExpression=http://127.0.0.1:8000/light-level;

Response:

{"result": {"light-level": 30}}

Send a POST (or other HTTP method) request to a REST endpoint:

set requestUrlExpression=<url>;HTTPMethod=<method>;value=<value>;

Example — set the room light level to 80:

set requestUrlExpression=http://127.0.0.1:8000/light-level;HTTPMethod=POST;value=80;

Response:

{"result": {"status": "ok"}}

Verify with GET:

get requestUrlExpression=http://127.0.0.1:8000/light-level;

Response:

{"result": {"light-level": 80}}

Send a GET request to an external API endpoint configured in the connector:

get requestUrlExpression=<path>;

Example — read the room light level from the configured base URL:

get requestUrlExpression=light-level;

Response:

{"result": {"light-level": 30}}

Send a POST (or other HTTP method) request to an external API endpoint:

set requestUrlExpression=<path>;httpMethod=<method>;value=<value>;

Example — set the room light level to 80:

set requestUrlExpression=light-level;httpMethod=POST;value=80;

Response:

{"result": {"status": "ok"}}

Verify with GET:

get requestUrlExpression=light-level;

Response:

{"result": {"light-level": 80}}

Read a file from the FTP server:

get filePath=<filePath>;

Example — read light_level.txt:

get filePath=./light_level.txt;

Response:

{"result": "30"}

Write a value to a file on the FTP server:

set filePath=<filePath>;value=<value>;

Example — update light_level.txt to 80:

set filePath=./light_level.txt;value=80;

Response:

{"result": "80"}

Verify with GET:

get filePath=./light_level.txt;

Response:

{"result": "80"}

Which variables are readable or writable depends entirely on what the Charge Point’s Device Model implements — not every Charge Point exposes every variable, and a request can come back as Rejected, UnknownComponent, or UnknownVariable instead of Accepted.

Read the current value of an OCPP variable:

get component=<component>;componentInstance=<instance>;evseId=<id>;variable=<variable>;variableInstance=<instance>;timeout=<seconds>;

Example — read the heartbeat interval of the Charging Station:

get component=OCPPCommCtrlr;variable=HeartbeatInterval

Write a new value to an OCPP variable:

set component=<component>;componentInstance=<instance>;evseId=<id>;variable=<variable>;variableInstance=<instance>;timeout=<seconds>;value=<value>;

Example — set the heartbeat interval to 30 seconds:

set component=OCPPCommCtrlr;variable=HeartbeatInterval;value=30

Verify with GET:

get component=OCPPCommCtrlr;variable=HeartbeatInterval

The Socket connector supports only the SET method — sending data to a TCP socket endpoint.

Send data to a TCP socket:

set address=<address>;port=<port>;encoding=<encoding>;value=<value>;

Example — send a light level of 80 to a sensor listening on 192.168.0.200:50003:

set address=192.168.0.200;port=50003;encoding=utf-8;value=80;

Response:

{"result": "ok"}

Socket SET — value sent and acknowledged by the TCP endpoint. Sensor side — the new value received by the device.

Read the value of a GATT characteristic:

get characteristicUUID=<uuid>;

The response contains the characteristic value decoded as UTF-8 text.

Example — read the manufacturer name characteristic:

get characteristicUUID=00002A29-0000-1000-8000-00805F9B34FB;

Response:

{"result": "EFENTO_GROUP"}

Write a value to a GATT characteristic:

set characteristicUUID=<uuid>;value=<value>;

Example:

set characteristicUUID=226CAA55-6476-4566-7562-66734470666D;value=1;

Response:

{"result": "Ok"}

The CAN connector supports only the SET method: sending a message to the CAN bus. A get request returns an error.

Send a CAN message:

set nodeId=<id>;type=<type>;byteorder=<byteorder>;isExtendedId=<isExtendedId>;value=<value>;

With type=hex, value is the message payload as hex digits, for example 0A1B. With type=string, the value is sent as ASCII text. Integer types take as many bytes as their size: 16int takes 2 bytes, and so on.

Example — send the light level 80 as one unsigned byte to node 0x400:

set nodeId=0x400;type=8uint;value=80;

Response:

{"result": {"success": true}}

As you can see in the screenshot below, the lightLevel telemetry value of the device has changed to 80:

get and set work the same way: both run an SQL query or call a stored procedure.

get query=<query>;value=<arg1>,<arg2>;with_result=<true|false>;
get procedure_name=<name>;value=<arg1>,<arg2>;with_result=<true|false>;

With with_result=true, the response contains the first row of the result set as an object with column names as keys, or null if the query returns no rows. A statement that returns no result set, such as UPDATE, gives an error with with_result=true. Without it, the response is {"result": {"success": true}}.

Example — read the latest value of a column:

get query=SELECT temperature FROM telemetry WHERE device = ? ORDER BY ts DESC LIMIT 1;value=thermostat-1;with_result=true;

Response, for example:

{"result": {"temperature": 18.04}}

Example — call the set_setpoint function to change the target temperature:

set procedure_name=set_setpoint;value=23.5;

Response:

{"result": {"success": true}}

On PostgreSQL, procedure_name works only for functions: a procedure fails with <name>() is a procedure.

Example — call a PostgreSQL procedure by passing a CALL statement in query:

set query=CALL <name>(?,?);value=<arg1>,<arg2>;

A procedure without output parameters returns no result set, so do not set with_result=true for it.

Read the value of an OID:

get oid=<oid>;timeout=<seconds>;

Example — read the system description:

get oid=1.3.6.1.2.1.1.1.0;

Response:

{"result": "Demo Device"}

Write a value to an OID:

set oid=<oid>;type=<type>;timeout=<seconds>;value=<value>;

Example — set the system location:

set oid=1.3.6.1.2.1.1.6.0;type=OCTETSTRING;value=Data center;

Response:

{"result": "Data center"}

Read the value of a group address:

get groupAddress=<groupAddress>;dataType=<dataType>;requestType=read;

Example — read the temperature from group address 1/0/6:

get groupAddress=1/0/6;dataType=temperature;requestType=read;

Response:

{"result": "21.4"}

Write a value to a group address:

set groupAddress=<groupAddress>;dataType=<dataType>;value=<value>;

Example — set the brightness on group address 1/0/9 to 50%:

set groupAddress=1/0/9;dataType=percentU8;value=50;

Response:

{"result": "50"}

The XMPP connector supports only the SET method: sending a message to the device.

Send a JSON message to the device:

set <key>=<value>;

Each <key>=<value> pair becomes a field of the message. Values are sent as strings.

Example — send the value 25 to the device:

set value=25;

The device receives {"value": "25"}.

Response:

{"result": "success"}