Wednesday, August 15, 2012

Functional Constraint CO “Control” missing in IEC 61850-7-2 Edition 2

Somebody asked me today: “I did not find the CO Functional Constraint among the Functional Constraint list in IEC61850-7-2{ed2.0}.pdf, section FunctionalConstraint (FC). Please advise what does it represent?”

In IEC 61850-7-2 Ed1, IEC 61850-7-3 Ed1, and IEC 61850-8-1 Ed1 the control model was described partly in 7-2, 7-3 and 8-1. Now we have the complete control model defined in IEC 61850-7-2 Ed2 – without any mapping issue! in IEC 61850-7-3 Ed2 we have defined for controllable data objects (CDCs: SPC, DPC, …) that the service is Control and the payload is as defined in IEC 61850-7-2 Ed2.

CDC: SPC, DPC, INC, ENC, BSC, ISC, APC, BAC adds the control service at the end of the CDCs for controllable data objects:


That is the reason why we have removed the FC=CO from IEC 61850-7-3 Ed2 (and IEC 61850-7-2 Ed2).

The FC=CO is introduced in the mapping in IEC 61850-8-1 Ed2.

From an implementation point of view (in MMS terms) it is more or less the same in Ed1 and Ed2 of the three parts. The description has changed – it is cleaner now … if you know where to find it … I agree it’s a bit confusing …

The Data Objects of CDC for settings like SPG, ING, … are not using the control services to set a value! These CDCs just support SetDataValues (which is a write in MMS …without the control state machines) and other services:


Hope that helps to understand the (mainly editorial) changes in the three parts 7-2 Ed2, 7-3 Ed2, and 8-1 Ed2.

1 comment:


Very very informative blog for utility communication network networks.
I loved it while reading.
Thank you Mr. Karlheinz Schwarz