Protocol Adapters

About the Protocol Adapters

The APM OT Connect Adapter Service can support several different Protocol Adapter modules, depending on the configuration of the corresponding OT Source. These Protocol Adapters are used to connect to a specific Process Historian or a server that complies with an OPC specification.

The OT Connect Adapter Service will configure and start the Protocol Adapter matching the Type and Protocol Connection parameters configured on the OT Source on the following:

Service Start
When the OT Source is reconfigured

Capabilities

Different Protocol Adapters, and even in some cases different implementations or versions of a Process Historian or OPC Server can support a variety of different capabilities when querying or subscribing to data.

The supported capabilities are listed on the table below:


Name	Supported action
LastReading	Query the OT Source for the last good Reading for a Tag.
StartToEndReadings	Query the OT Source for all Readings between a Start and End time.
SubscribeReadings	Establish a subscription to new Readings for a Tag, which can be used to update Health Indicators or trigger Policy Instances unsolicited.
BeforeEndReadings	Query the OT Source for a specified number of readings before an End time.
SubscribeReadings	Subscribe to a Tag for updated Readings with a new Timestamp or Value.

The Capabilities of an OT Source are reported as part of the Connection Status.

Simulation

The Simulation Protocol Adapter is provided for testing and exploration. Rather than connecting to an actual process historian, it provides simulated tag metadata and Readings for all Capabilities.

ProtocolConnection

The Simulation Protocol Adapter is not configurable.

OPC-HDA

The OPC-HDA Protocol Adapter can connect to an OPC Classic HDA 1.20 server.

Important: The OPC-HDA Protocol Adapter does not support remote connections. The OPC-HDA server must be installed on the same server, preferably running under the same user account as the Adapter Service.

Vendors have implemented different elements of the specification, so it is important to review the Connection Status or OT Source Capability Utility report to understand what Capabilities are available from the server you want to integrate with APM.

A fully supported OPC server can provide the following:

LastReading
SubscribeReadings
GetStartEndReadings

ProtocolConnection

The OPC-HDA ProtocolAdapter requires the ProgId to be configured.

If the correct ProgId is not provided, the ProtocolAdapter will log an exception report on all available OPC-HDA ProgIds on the server on startup.

Optionally, the BatchSize can be configured to support OPC-HDA servers with an unusually low or high limit to the number of records that can be returned for a single request.

Note: Decrease this setting if you observe E_MAXEXCEEDED OPC Errors when viewing the trend charts or when running the OT Source Capability Utility. The default value is used as 10,000, if the BatchSize is set to 0.

OSI PI

The OSI PI protocol adapter can connect to PI Server 2010 and later, using the Asset Framework (AF) protocol. This allows OT Connect to support PI without an intervening OPC server. OSI PI protocol adapter requires the PI AF Client to be installed on the OT Connect Process Data server. The AF protocol offers improved security, performance, and reliability. Therefore, it is recommended to use this adapter to connect to the OSI PI servers.

The OSI PI protocol adapter offers the following Capabilities:

LastReading
SubscribeReadings
GetStartEndReadings
GetBeforeEndReadings

Configure the OSI PI Protocol Adapter

Install PI AF Client. For information on installing the PI AF client, refer to the OSIsoft documentation.
Configure the OT Source.

Table 1. Connection Details
Host Name	Hostname or the FQDN of the target server. The host name must exactly match with the name that is configured in the System Explorer.
User Name	Windows user configured with a PI mapping.
Password	Windows password.

GED Historian

The Proficy Historian Protocol Adapter can connect to Proficy Historian 4.0 and later through the Client Access API. This allows OT Connect to support the Proficy Historian without an intervening OPC server. It requires the Client Access Assemblies to be installed on the OT Connect Process Data server.

It is recommended to use this adapter to connect to the Proficy Historian servers whenever possible, as the Client Access API offers improved security, performance, and reliability.

The Proficy Historian Protocol Adapter offers the following Capabilities:

LastReading
SubscribeReadings
GetStartEndReadings
GetBeforeEndReadings

Note: Health Indicators, Triggered Policies, and Last Reading are only supported on Proficy Historian through the Proficy Historian Protocol adapter. These capabilities are not available through OPC.

Configure the Proficy Historian Protocol Adapter

Install the Historian Client Tools by selecting the Client Access Assemblies. For information on installing the Historian Client Tools, refer to the Proficy Historian documentation. Other features are not required and the Historian Data Archiver can be on another server.
Configure the OT Source.

Table 2. Connection Details
Host Name	Hostname or FQDN of the target server. The host name must match exactly with the name that was provided when installing the target historian.
User Name	Windows user with iH Readers membership on the Process Historian server.
Password	Windows password.

OPC-DA

The OPC-DA Protocol Adapter can connect to OPC Classic DA 3.0 servers

Important: The OPC-DA Protocol Adapter does not support remote connections. The OPC-DA server must be installed on the same server, preferably running under the same user account as the Adapter Service.

Note:

While some OPC-DA 2.0 – 2.05a servers are forward compatible, and the OT Connect OPC-DA ProtocolAdapter can work with them, this varies between vendors, and is not guaranteed.

Only OPC 3.0 servers are officially supported by OT Connect.

The OSI Pi OPC-DA Server is an example of a 2.05a server that is not compatible with OT Connect.

Vendors have implemented different elements of the specification. So, it is important to review the Connection Status or OT Source Capability Utility report to understand what Capabilities are available from the server that you want to integrate with APM.

For OPC-DA, the most common limitation is properties, such as Description or RawUom not being available for Tag Sync, which will complete with only the Tag Name and DataType.

An OPC-DA server can provide the following capabilities:

LastReading
SubscribeReadings

ProtocolConnection

The OPC-DA ProtocolAdapter requires the ProgId to be configured.

If the correct ProgId is not provided, the ProtocolAdapter will log an exception report on all available OPC-DA ProgIds on the server on startup.

Note: For a Health Indicators Subscription that uses data from an OT Source, the recommended approach is to use the DA protocol. The HDA protocol will aggregate the readings for a period of time and may not be perform as expected. This may be the case where too many Health Indicators are setup or the number of readings for the period of time is very large.