opc

OPC (Open Platform Communications) is an interoperability standard for secure data exchange in automation and other industries. The DolphinDB opc plugin has implemented the OPC DA 2.05a Specification, which can be used to access and collect data from OPC servers in the automation industry.

Installation (with installPlugin)

Required server version: DolphinDB 2.00.10 or higher

Supported OS: Windows.

Installation Steps:

(1) Use listRemotePlugins to check plugin information in the plugin repository.

Note: For plugins not included in the provided list, you can install through precompiled binaries or compile from source. These files can be accessed from our GitHub repository by switching to the appropriate version branch.

login("admin", "123456")
listRemotePlugins()

(2) Invoke installPlugin for plugin installation.

installPlugin("opc")

(3) Use loadPlugin to load the plugin before using the plugin methods.

loadPlugin("opc")

Methods References

Currently, the OPC plugin only supports OPC 2.0 protocol and does not support asynchronous read and write operations.

getServerList

Syntax

getServerList(host)

Details

Get an OPC server.

Return a table with two columns. The first column is the progID indicating the identification of the server and the second is the CLSID of the server. Please configure DCOM settings for both OPC Client and Server.

Parameters

  • host: A STRING scalar indicating the IP address, such as "127.0.0.1".

Examples

opc::getOpcServerList("desk9")

connect

Syntax

connect(host, serverName，[reqUpdateRate_ms=100])

Details

Connect to an OPC Server.

Return a connection object that can be explicitly closed using the close function, or automatically released when the reference count is 0. Please configure DCOM settings for both OPC Client and Server.

Parameters

  • host: A STRING scalar indicating the IP address.
  • serverName: A STRING scalar indicating the name of the OPC server.
  • reqUpdateRate_ms: An integer indicating the request update rate in milliseconds. The default value is 100.

Examples

connection = opc::connect(`127.0.0.1,`Matrikon.OPC.Simulation.1,100)

readTag

Syntax

readTag(connection, tagName, [table])

Details

Read the values of the tags synchronously. An OPC connection needs to be established before reading.

Parameters

  • connection: An object returned by connect.
  • tagName: A STRING scalar/vector indicating the name of tags.
  • table: A table or an array of tables used to store the result of reading. The number of tables must be the same as the number of tags when it is an array.
    • If it is a table, all the tag values are inserted into this table.
    • If it is an array of multiple tables, the value read by each tag is inserted into the corresponding table.
    • If it is not specified, readTag returns a table containing all the tag values by default.

Examples

t = table(200:0,`tag`time`value`quality, [SYMBOL,TIMESTAMP, DOUBLE, INT])
opc::readTag(conn, "testwrite.test9",t)
opc::readTag(conn, ["testwrite.test5","testwrite.test8", "testwrite.test9"],t) 
tm = table(200:0,`time`tag1`quality1`tag2`quality2, [TIMESTAMP,STRING, INT,INT,INT])
opc::readTag(conn, ["testwrite.test1","testwrite.test4"],tm) 
t1 = table(200:0,`tag`time`value`quality, [SYMBOL,TIMESTAMP, STRING, INT])
t2 = table(200:0,`tag`time`value`quality, [SYMBOL,TIMESTAMP, INT, INT])
t3 = table(200:0,`tag`time`value`quality, [SYMBOL,TIMESTAMP, DOUBLE, INT])
opc::readTag(conn, ["testwrite.test1","testwrite.test4", "testwrite.test9"],[t1,t2,t3])

writeTag

Syntax

writeTag(connection, tagName, value)

Details

Write values to the specified tags.

Parameters

  • connection: An object returned by connect.
  • tagName: A STRING scalar/vector indicating the name of tags.
  • value: The values or array to be written to the tags.

Examples

opc::writeTag(conn,"testwrite.test1",[1.112,0.123,0.1234])
opc::writeTag(conn,["testwrite.test5","testwrite.test6"],[33,11])

subscribe

Syntax

subscribe(connection, tagName, handler)

Details

Subscribe to the values of the tags from the OPC server.

Parameters

  • connection: An object returned by connect.
  • tagName: A STRING scalar/vector indicating the name of tags.
  • handler: A function to be called or a table where the subscribed values are written to.

Examples

t1 = table(200:0,`tag`time`value`quality, [SYMBOL,TIMESTAMP, STRING, INT])
conn1=connect(`127.0.0.1,`Matrikon.OPC.Simulation.1,100)
opc::subscribe(conn1,".testString", t1)

t2 = table(200:0,`tag`time`value`quality, [SYMBOL,TIMESTAMP, DOUBLE, INT])
conn2=connect(`127.0.0.1,`Matrikon.OPC.Simulation.1,100)
opc::subscribe(conn2,[".testReal8",".testReal4"], t2)

def callback1(mutable t, d) {
	t.append!(d)
}
t3 = table(200:0,`tag`time`value`quality, [SYMBOL,TIMESTAMP, BOOL, INT])
conn10 = connect(`127.0.0.1,`Matrikon.OPC.Simulation.1,10)
opc::subscribe(conn10,".testBool", callback1{t3})

getSubscriberStat

Syntax

getSubscriberStat()

Details

Get all the subscription information.

Return a table with the following columns:

  • subscriptionId: Subscription ID.
  • user: The session user who creates the subscription.
  • host: The site of the OPC server.
  • serverName: The name of the OPC server.
  • tag: The subscription tag.
  • createTimestamp: The time when the subscription is created.
  • receivedPackets: The number of packets received.
  • errorMsg: The latest error message.

Parameters

None.

Examples

t = opc::getSubscriberStat()for(sub in t[`subscriptionId]){unsubscribe(sub)}

Unsubscribe

Syntax

unsubcribe(subscription)

Details

Unsubscribe from the OPC server.

Parameters

  • subscription: The subscription ID returned by connect or getSubscriberStat.

Examples

opc::unsubcribe(subscription)

close

Syntax

close(connection)

Details

Close the connection to the OPC server.

Parameters

  • connection: An object returned by connect.

Example

opc::close(connection)