OPC DA in Go

Read and write process and automation data in Go from an OPC server for monitoring and data analysis purposes (OPC DA protocol).

go get github.com/konimarti/opc

Usage

client, _ := opc.NewConnection(
	"Graybox.Simulator", 		// ProgId
	[]string{"localhost"}, 		// Nodes
	[]string{"numeric.sin.float"}, 	// Tags
)
defer client.Close()
client.ReadItem("numeric.sin.float")

browser, _ := opc.CreateBrowser(
	"Graybox.Simulator", 		// ProgId
	[]string{"localhost"}, 		// Nodes	
)
opc.PrettyPrint(browser)

Installation

• go get github.com/konimarti/opc

Troubleshooting

• OPC DA Automation Wrapper 2.02 should be installed on your system (OPCDAAuto.dll or gbda_aut.dll); the automation wrapper is usually shipped as part of the OPC Core Components of your OPC Server.
• You can get the Graybox DA Automation Wrapper here. Follow the installation instruction for this wrapper.
• Depending on whether your OPC server and automation wrapper are 32-bit or 64-bit, set the Go architecture correspondingly:
  • For 64-bit OPC servers and wrappers: DLL should be in C:\Windows\System32, use $ENV:GOARCH="amd64"
  • For 32-bit OPC servers and wrappers: DLL should be in C:\Windows\SysWOW64, use $ENV:GOARCH="386"
• Make sure to have correct DCOM settings on your local and remote computers: Dcomcnfg.exe

Reporting Issues

• If you find a bug in the code, please create an issue and suggest a solution how to fix it.
• Issues that are related to connection problems are mostly because of a faulty installation of your OPC automation wrapper or some peculiarties of your specific setup and OPC installation. Since we cannot debug your specific situation, these issues will be directly closed.

Debugging

• Add opc.Debug() before the opc.NewConnection call to print more debug-related information.

Testing

• Start Graybox Simulator v1.8. This is a free OPC simulation server and require for testing this package. It can be downloaded here.
• If you use the Graybox Simulator, set $GOARCH environment variable to "386", i.e. enter $ENV:GOARCH=386 in Powershell.
• Test code with go test -v

Example

package main

import (
	"fmt"
	"github.com/konimarti/opc"
)

func main() {
	client, _ := opc.NewConnection(
		"Graybox.Simulator", // ProgId
		[]string{"localhost"}, //  OPC servers nodes
		[]string{"numeric.sin.int64", "numeric.saw.float"}, // slice of OPC tags
	)
	defer client.Close()

	// read single tag: value, quality, timestamp
	fmt.Println(client.ReadItem("numeric.sin.int64"))

	// read all added tags
	fmt.Println(client.Read())
}

with the following output:

{91 192 2019-06-21 15:23:08 +0000 UTC}
map[numeric.sin.int64:{91 192 2019-06-21 15:23:08 +0000 UTC} numeric.saw.float:{-36.42 192 2019-06-21 15:23:08 +0000 UTC
}]

Applications

opc-cli

• opc-cli is a command-line interface to work with OPC servers: list available OPC servers, browse OPC tags on server, and read/write OPC tags.

• Install it with go install github.com/konimarti/opc/cmds/opc-cli

  • List OPC servers on a specific node:

    $ opc-cli.exe list localhost
    Found 3 server(s) on 'localhost':
    Graybox.Simulator.1
    INAT TcpIpH1 OPC Server
    Prosys.OPC.Simulation
    

  • Browse OPC tags (in sub-branch):

    $ opc-cli.exe browse localhost Graybox.Simulator.1 textual
    textual
       - textual.color
       - textual.number
       - textual.random
       - textual.weekday
    

  • Write to OPC tag:

    $ opc-cli.exe write localhost Graybox.Simulator.1 options.sinfreq 0.01
    

  • Read OPC tags:

    $ opc-cli.exe read localhost Graybox.Simulator.1 options.sinfreq numeric.sin.float
    map[options.sinfreq:{0.05 192 2019-06-21 15:26:02 +0000 UTC} numeric.sin.float:{22.916641 192 2019-06-21 15:26:02 +0000 UTC}]
    

OPCAPI

• Application to expose OPC tags with a JSON REST API.

  • Install the app: go install github.com/konimarti/opc/cmds/opcapi

  • Create config file:

    [config]
    allow_write = false
    allow_add = true
    allow_remove = true
    
    [opc]
    server = "Graybox.Simulator"
    nodes = [ "localhost" ]
    tags = [ "numeric.sin.float", "numeric.saw.float" ]
    
    

  • Run app:

    $ opcapi.exe -conf api.conf -addr ":4444"
    

  • Access API:

    • Get tags:

      $ curl.exe -X GET localhost:4444/tags
      {"numeric.saw.float":-21.41,"numeric.sin.float":62.303356}
      

    • Add tag:

      $ curl.exe -X POST -d '["numeric.triangle.float"]' localhost:4444/tag
      {"result": "created"}
      

    • Remove tag:

      $ curl.exe -X DELETE localhost:4444/tag/numeric.triangle.float
      {"result": "removed"}
      

OPCFLUX

• Application to write OPC data directly to InfluxDB.

  • Install the app: go install github.com/konimarti/opc/cmds/opcflux

  • Create InfluxDB database "test"

  • Create config file: Put OPC tags in []. This is required for the expression evaluation. Any calculation can be performed that can evaluated.

    ---
    server: "Graybox.Simulator"
    nodes: ["localhost", "127.0.0.1"]
    monitoring: ""
    influx:
     addr: "http://localhost:8086"
     database: test
     precision: s
    measurements: 
     numeric:
       - tags: {type: sin}
         fields: {float: "[numeric.sin.float]", int: "[numeric.sin.int32]"}
       - tags: {type: saw}
         fields: {float: "[numeric.saw.float]", int: "[numeric.saw.int32]"}
       - tags: {type: calculation}
         fields: {float: "[numeric.triangle.float] / [numeric.triangle.int32]"}
     textual:
       - tags: {type: color}
         fields: {text: "[textual.color]", brown: "[textual.color] == 'Brown'"}        
       - tags: {type: weekday}
         fields: {text: "[textual.weekday]"}        
    

  • Run app: opcflux.exe -conf influx.yml -rate 1s

Credits

This software package has been developed for and is in production at Kalkfabrik Netstal.