---
title: OPC-DA collector
slug: reference/opc-da-collector
docTags: 
createdAt: 2025-09-09T09:35:38.514Z
---

## Basic settings

The collector settings are used by the collector to connect to the OPC-DA server.

### ProgID

**Description**: The programmatic identifier of the OPC-DA server.
**Required**: yes
**Example**: Matrikon.OPC.Simulation.1

### Node

**Description**: The node of the OPC-DA server.
**Required**: yes
**Default**: localhost

:::hint{type="warning"}
This setting was called `Nodes` and accepted a comma separated list before collector version 3.0.0, which removed support for multiple OPC-DA servers. A collector upgraded from an earlier version keeps only the first node of the old list.
:::

### CollectionSource

**Description**: The source from which to collect data.
**Required**: yes
**Options**: Cache | Device
**Default**: Cache

## Advanced settings

### EscapeNonPrintableCharacters

**Description**: When enabled, every string value read from the OPC-DA server is quoted and its non-printable characters are escaped before it is stored. Turn this off to store the raw string.
**Required**: no
**Default**: true

### HeartBeatInterval

**Description**: The interval in milliseconds of the liveness probe that decides when the connection is declared dead and the collector reconnects. This is the mechanism behind the `OPC-DA server unavailable` health message.
**Required**: no
**Default**: 10000
**Minimum**: 5000

## Measurement settings

The measurement settings reflect the configuration possibilities for mapping a measurement to an OPC-DA tag.

### ItemID

**Description**: Fully qualified OPC-DA item name.
**Required**: yes
**Example**: Factry.Saw-1

### CollectionType

**Description**: The way this measurement should be collected from the OPC-DA server.
**Required**: yes
**Default**: polled
**Options**: polled | monitored

:::hint{type="info"}
Checkout the [data collection methods](docId\:kp91_LGM4jw-dIQr0a6Z2) section for more information.
:::

### CollectionInterval

**Description**: The interval in milliseconds at which this measurement should be collected.
**Required**: yes
**Default**: 5000

### CollectionOffset

**Description**: The offset in milliseconds, relative to the 0th second of a minute, at which this measurement should be collected. Only relevant for polled measurements.
**Required**: yes
**Default**: 0

## Data collection methods

The OPC-DA collector has 2 methods to collect measurement data, which are referred to as the collection type of a measurement.

### Polling

Polled measurements are read every x milliseconds (minimum of 1000ms), which is the collection interval. This data collection method should be used for measurements for which the value changes regularly over time. Configure the interval depending on how frequent you want to collect data points for this measurement.

### Monitoring

Monitored measurements collect data on every change of the measurements value. The measurement is polled at its own collection interval, raised to the minimum of 1000ms if configured lower, and each sample is compared against the last stored value; unchanged samples are dropped. A change that happens between two polls is therefore not seen, so keep the collection interval short enough for the changes you care about. Typically, monitored measurements are configured for boolean or string data types that indicate an equipments state, f.e. for a valve that opens and/or closes only a few times per hour.

## Collector health

OPC-DA Specific collector health messages. See [here](docId\:CUxTvhAhQ2yyJjjwAtDH8) for all generic collector health messages.

You can find the collector health and the collector health history in the detail view on the right, when selecting a collector in the historian admin webpage.

### Error connecting to OPC-DA server

The collector failed to connect to the OPC-DA server. This indicates that a collector setting hasn’t been configured correctly or that the OPC-DA server isn’t reachable.

### OPC-DA server unavailable

The OPC-DA client lost connection with the OPC-DA server.

## Limitations

It is currently not possible to read arrays from the OPC-DA server.