<!-- ---
title: opcxmlda-driver
description: 
published: true
date: 2021-08-22T20:06:17.726Z
tags: 
editor: markdown
dateCreated: 2021-08-15T02:46:54.526Z
---
 -->

# OPC XML-DA Driver

## Overview

Fully configurable OPC XML-DA driver built on top of [base-driver](https://github.com/Ladder99/base-driver), [QuickOPC](https://www.opclabs.com/products/picoopc/227-products/quickopc), and [MTConnect .NET SDK](https://github.com/mtconnect/dot_net_sdk) libraries.  

Perfect for pulling data from Simotion drives running on Simatic Step 7 before OPC-UA was made available.

## Source

[Github Repository](https://github.com/Ladder99/opcxmlda-driver)

## Output

### SHDR

Handler `l99.driver.opcxmlda.handlers.SHDR, opcxmlda` outputs data in SHDR format to an MQTT broker and also is available at the TCP port defined in configuration (default: 7878).

<!-- ![SHDR MQTT](_images/shdr_mqtt.gif) -->

![SHDR TCP](_images/shdr_tcp.gif)

### Splunk Metric

Handler `l99.driver.opcxmlda.handlers.SplunkMetric, opcxmlda` outputs data in Splunk metric format to an MQTT broker.

![SPLUNK MQTT](_images/splunk_mqtt.gif)

## Configuration
  
```yml
machines:
  - id: demo
    enabled: !!bool true
    type: l99.driver.opcxmlda.OpcxmldaMachine, opcxmlda
    strategy: l99.driver.opcxmlda.collectors.Basic01, opcxmlda
    handler: l99.driver.opcxmlda.handlers.SHDR, opcxmlda
```

The `broker` section defines the MQTT broker settings.  

```yml
    broker:
      enabled: !!bool true
      net_ip: 10.20.30.102
      net_port: !!int 1883
      auto_connect: !!bool true
      publish_status: !!bool true
      publish_arrivals: !!bool true
      publish_changes: !!bool true
      publish_disco: !!bool true
      disco_base_topic: opcxmlda
```

The machine type `data` section identifies individual OPC XML-DA items.  The `shdr` section is specific to the SHDR handler to assist with transmitting the data to an MTConnect Agent.  

`shdr.name` - MTConnect DataItem name  
`shdr.category` - MTConnect DataItem category (sample,event,message,condition)  
`shdr.eval` - Lua evaluation context and pre-processor

```yml
    l99.driver.opcxmlda.OpcxmldaMachine, opcxmlda:
      sweep_ms: !!int 1000
      net_uri: http://opcxml.demo-this.com/XmlDaSampleServer/Service.asmx
      net_timeout_s: !!int 3
      data:
        - Dynamic/Analog Types/Double:
            shdr:
              name: analog_double
              category: sample
              eval: |
                --print(JObject.FromObject(dataitems):ToString());
                if current_value == 'UNAVAILABLE' then
                  print(name .. ' is available')
                  return new_value
                else
                  print(name .. ' = ' .. current_value .. ' + ' .. new_value)
                  return current_value + new_value
                end
        - Dynamic/Analog Types/Int:
            shdr:
              name: analog_int
              category: sample
              eval: |
                print('analog_int value: ' .. dataitems["analog_int"].Value);
                return new_value;
        - Dynamic/Analog Types/Double[]:
        - Static/Simple Types/String:
            shdr:
              name: simple_string
              category: message
              eval: |
                random_code = math.random(100,999);
                dataitem.Code = tostring(random_code);
                return new_value;
        - Static/Simple Types/DateTime:
            shdr:
              name: simple_datetime
              category: event
        - Static/ArrayTypes/Object[]:
        - Dynamic/Analog Types/Fools/Guildenstern:
        - Dynamic/Enumerated Types/Gems:
        - SomeUnknownItem:
```

Handler sections provide additional configuration.  In this case the SHDR handler identifies the MTConnect Adapter to listen on as well as additional MTConnect DataItems that might not be available at the OPC server.

```yml
    l99.driver.opcxmlda.handlers.SHDR, opcxmlda:
      port: !!int 7878
      verbose: !!bool true
      lua_head: |
        luanet.load_assembly 'System';
        luanet.load_assembly 'Newtonsoft.Json';
        JObject = luanet.import_type 'Newtonsoft.Json.Linq.JObject';
      data:
        - avail:
            shdr:
              name: avail
              category: event
              eval: |
                return "AVAILABLE";
```

## Lua Evaluation Context

The Lua script generated from the `config.yml` file is shown below.  A function is defined for every MTConnect DataItem.  

### Function Signature

`this` - Lua table  
`name` - DataItem name  
`current_value` - DataItem current value  
`new_value` - new value arriving from OPC server  
`dataitem` - reference to the `MTCDataItem` object  
`dataitems` - reference to the `MTCDataItem` collection  

```lua
luanet.load_assembly 'System';
luanet.load_assembly 'Newtonsoft.Json';
JObject = luanet.import_type 'Newtonsoft.Json.Linq.JObject';

user =  {}

function user:avail(this, name, current_value, new_value, dataitem, dataitems)
    return \"AVAILABLE\";
end

function user:analog_double(this, name, current_value, new_value, dataitem, dataitems)
    --print(JObject.FromObject(dataitems):ToString());
    
    if current_value == 'UNAVAILABLE' then
      print(name .. ' is available')
      return new_value
    else
      print(name .. ' = ' .. current_value .. ' + ' .. new_value)
      return current_value + new_value
    end
end

function user:analog_int(this, name, current_value, new_value, dataitem, dataitems)
    print('analog_int value: ' .. dataitems[\"analog_int\"].Value);
    return new_value;
end

function user:simple_string(this, name, current_value, new_value, dataitem, dataitems)
    random_code = math.random(100,999);
    dataitem.Code = tostring(random_code);
    return new_value;
end
```