Built-in GET/SET RPC Methods

Every telemetry and attribute parameter has GET and SET methods automatically, based on the path defined in the connector configuration.

For example, given a timeseries entry:

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

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

get ns=3;i=1001;

Response:

{"result": 25.34}

Write a numeric value to a node:

set ns=3;i=1001; value=23;

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

set ns=3;i=1008; value=T3000;

Response:

{"success": "true", "code": 200}

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": {"value": 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": {"value": "80"}}

Verify by reading the register back:

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

Response:

{"result": {"value": 80}}

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

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

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

get requestTopicExpression=data/get_light_level;responseTopicExpression=data/response;value=${params};

Publish a message to an MQTT topic:

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

Example — set 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=${params};

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>;

At least one of value or priority must be provided. If value is omitted, the connector sends a relinquish command with a Null value.

Example — set the room light level to 30.9:

set objectType=analogValue;objectId=1;propertyId=presentValue;value=30.9;

Response:

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

Verify with GET:

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

Response:

{"result": "30.9"}

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
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 S7 PLC 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>;value=<value>;

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;value=${params};

Response:

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

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

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

Example — set the room light level to 80:

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

Response:

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

Verify with GET:

get requestUrlExpression=http://127.0.0.1:8000/light-level;value=${params};

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>;value=<value>;httpMethod=<method>;

Example — set the room light level to 80:

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

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": "{\"success\": true}"}

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>;variable=<variable>

Example — read the Charging Station’s availability state:

get component=ChargingStation;variable=AvailabilityState

Write a new value to an OCPP variable:

set component=<component>;variable=<variable>;value=<value>

Example — set the Charging Station’s availability state to unavailable:

set component=ChargingStation;variable=AvailabilityState;value=Unavailable

Verify with GET:

get component=ChargingStation;variable=AvailabilityState

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>;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;value=80;

Response:

{"result": "ok"}

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