OPC Data Access

OPC Data Access (OPC DA)International standard| OPC DA specification

|

Developed by| OPC Foundation
Introduced| August 1996; 29 years ago (1996-08)
Industry| Operational technology and Information technology
Compatible hardware| Windows
Superseded by| OPC Unified Architecture

The OPC Data Access Specification is the first of a group of specifications known as the OPC Classic Specifications.[1]

OPC Data Access is a group of client–server standards that provides specifications for communicating real-time data from data acquisition devices such as PLCs to display and interface devices like Human–Machine Interfaces (HMI), SCADA systems[2] and also ERP/MES systems.[3] The specifications focus on the continuous communication of data.

The OPC Data Access specification is also known as OPC DA. OPC DA deals only with real-time data and not historical data (for historical data you need to use OPC Historical Data Access, or OPC HDA) or events (for Alarms and Events you need to use OPC Alarms and Events, or OPC AE). There are three attributes associated with OPC DA data. These are

1. a value,
2. the quality of the value, and
3. a timestamp.

The OPC DA specification states that these three attributes have to be returned to an OPC client making a request. Therefore, if the data source is not capable of providing a timestamp, for example, the OPC DA server must create a timestamp.

The OPC Classic specifications are based on the Microsoft COM technology[4] and define a C/C++ interface. A standard Automation wrapper interface is also defined for access from Visual Basic, Delphi and other automation-enabled languages.[5] Several vendors offer .NET toolkits to make the OPC interface accessible in .NET applications.

The newer OPC .NET (OPC Xi) specification is based on WCF (Windows Communication Foundation) and defines a .NET interface with the functionality of the OPC Classic specifications OPC DA, OPC HDA and OPC AE (Alarms&Events).[6]

The more recent OPC Unified Architecture allows the same functionality but offers platform independence and optionally complex information modelling capabilities.[7]

## See also

* OPC Foundation
* Distributed Component Object Model
* OPC Unified Architecture

## References

1. ↑ "Members". https://opcfoundation.org/developer-tools/specifications-classic/data-access/.
2. ↑ "What is OPC?". https://opcfoundation.org/about/what-is-opc/.
3. ↑ Mahalik, Nitaigour P. (2013-03-09). Fieldbus Technology: Industrial Network Standards for Real-Time Distributed Control. Springer. ISBN 9783662072196. https://books.google.com/books?id=8Lj8CAAAQBAJ&q=ERP/MES "OPC DA" OR "OPC Data Access"&pg=PA352.
4. ↑ "Classic". https://opcfoundation.org/about/opc-technologies/opc-classic/.
5. ↑ "Members". https://opcfoundation.org/developer-tools/developer-kits-classic/automation-wrapper/.
6. ↑ ".NET 4.0 (WCF) | OPC Foundation". https://opcfoundation.org/about/opc-technologies/opc-net-4-0/.
7. ↑ "Unified Architecture". https://opcfoundation.org/about/opc-technologies/opc-ua/.

## External links

* OPC Programmers' Connection

* v
* t
* e

Automation protocols

Process automation|

* AS-i
* BSAP
* CC-Link Industrial Networks
* CIP
* CAN bus
* CANopen
* DeviceNet
* ControlNet
* DF-1
* DirectNET
* EtherCAT
* Ethernet Global Data (EGD)
* Ethernet Powerlink
* EtherNet/IP
* Factory Instrumentation Protocol
* FINS
* FOUNDATION fieldbus
* H1
* HSE
* GE SRTP
* HART Protocol
* Honeywell SDS
* HostLink
* INTERBUS
* IO-Link
* MECHATROLINK
* MelsecNet
* Modbus
* Optomux
* PieP
* Ethernet Powerlink
* Profibus
* PROFINET IO
* RAPIEnet
* SERCOS interface
* SERCOS III
* Sinec H1
* SynqNet
* TTEthernet

Industrial control system|

* MTConnect
* OPC DA
* OPC HDA
* OPC UA

Building automation|

* 1-Wire
* BACnet
* C-Bus
* CEBus
* DALI
* DSI
* DyNet
* Factory Instrumentation Protocol
* KNX
* LonTalk
* Modbus
* oBIX
* VSCP
* X10
* xAP
* xPL
* ZigBee

Power-system automation|

* IEC 60870
* IEC 60870-5
* IEC 60870-6
* DNP3
* Factory Instrumentation Protocol
* IEC 61850
* IEC 62351
* Modbus
* Profibus

Automatic meter reading|

* ANSI C12.18
* IEC 61107
* DLMS/IEC 62056
* M-Bus
* Modbus
* ZigBee

Automobile / Vehicle|

* AFDX
* ARINC 429
* CAN bus
* ARINC 825
* SAE J1939
* NMEA 2000
* FMS
* Factory Instrumentation Protocol
* FlexRay
* IEBus
* J1587
* J1708
* Keyword Protocol 2000
* Unified Diagnostic Services
* LIN
* MOST
* VAN
* UAVCAN

0.00

(0 votes)

Original source: https://en.wikipedia.org/wiki/OPC Data Access. Read more

|

Retrieved from "https://handwiki.org/wiki/index.php?title=Engineering:OPC_Data_Access&oldid=1041602"
*[v]: View this template
*[t]: Discuss this template
*[e]: Edit this template