Communication Specifications

Introduction

The following specifications describe both the IEC61850 communication and the capacities of the 140 NOP 850 00 module.

Data In versus Data Out

The terms data in and data out, as used in this topic, refer to the flow of data from the point of view of the 140 NOP 850 00 module IED, and vary depending on the role of the device as client or server.

Data In: the 140 NOP 850 00 module receives a data update from its connected devices, then synchronizes data with the CPU:
- As server: the 140 NOP 850 00 module receives a command from a control object, or from a buffered report, unbuffered report, or GOOSE.
- As client: the 140 NOP 850 00 module receives a report/GOOSE response to a previous read request.
Data Out: the 140 NOP 850 00 module receives a data update from the CPU, then propagates the data among its connected devices:
- As server: the 140 NOP 850 00 module sends a buffered report, unbuffered report, or GOOSE.
- As client: the 140 NOP 850 00 module issues a control object command, or a buffered report, unbuffered report, or GOOSE.

IEC61850 Messaging Specifications

The 140 NOP 850 00 module presents the following IEC61850 messaging features:

Feature		Capacity
Client
	Polling period per IED	1000 ms (default; configurable)
	Maximum number of data attributes	100001 data attributes
	Maximum number of concurrent IED connections	16 connections (provided the maximum of 10000 data attributes is not reached)
	Maximum number of words for data in flow variables	20002, 3, 5 words
	Maximum number of words for data out flow variables	20003, 4 words
Server
	Maximum number of concurrent client connections	16 connections
	Maximum number of data sets	100 data sets
	Maximum number of data attributes per data set	256 data attributes per data set
	Maximum number of data attributes	100001 data attributes
	Maximum number of virtual logical devices within an IED	16 logical devices
	Maximum number of report control blocks within an IED	64 total buffered plus unbuffered report control block instances
	Maximum number of instances of a single buffered control block	8 (serving 8 clients)
	Maximum buffer size of each buffered control block	16k bytes
	Maximum number of control blocks for GOOSE publishing	4 control blocks
	Maximum number of inputs in a GOOSE data set	256 inputs (provided the length of the message does not exceed one Ethernet frame)
	Maximum number of words for data in flow variables	20002, 3 words
	Maximum number of words for data out flow variables	20003, 4 words
1. The maximum number of data attributes includes the sum of client and server data attributes. 2. The maximum number of input words includes the sum of client and server input words. 3. The maximum number of variables depends on the data types included in the application, because the lengths of different data types varies. 4. The maximum number of output words includes the sum of client and server output words. 5. Module memory contains the most current (real-time) value for data in flow.

NOTE: IEC61850 communications are given a higher priority than Modbus TCP communications.

Explicit Messaging Specifications

The 140 NOP 850 00 module presents the following Modbus TCP explicit messaging features:

Feature		Capacity
Client
	maximum number of simultaneous connections	16 connections
	maximum number of concurrent requests	16 requests
Server
	maximum number of requests that can be transferred to the CPU per scan	12 requests
	maximum number of simultaneous connections	16 connections
Maximum message size
	read	250 bytes (125 words) excluding header
	write	240 bytes (120 words) excluding header
Maximum Explicit I/O memory allocation size
	Maximum number of allocated words	4000 (less memory allocated to implicit data in flow and out flow variables)

Comparing Standard Data Types: Control Expert and IEC61850 Data Types

The following list presents IEC61850 standard data types and the comparable data type used by Control Expert:

Control Expert Standard	Comparable IEC61850 Standard
Data Type	Data Type	Support by
Data Type	Data Type	Server	Client
WORD	BITSTRING	√	√
BOOL1	BOOLEAN	√	√
WORD	CODED ENUM	√	√
WORD	Dbpos	√	√
WORD	ENUMERATED	√	√
INT	INT8	√	√
BYTE	INT8U	√	√
INT	INT16	√	√
UINT	INT16U	√	√
DINT	INT32	√	√
UDINT	INT32U	√	√
Timestamp	TIME850FORMAT	√	√
1. In Control Expert, a BOOL occupies one BYTE.

BITSTRING

IEC61850 supports trigger, option, and quality report elements in BITSTRING format. Control Expert maps BITSTRING to the WORD data type. In each of the following structures, Bit0 is the most significant bit.

Trigger option of report structure: The following bits indicate the stated trigger value when equal to 1:

Bit0	Bit1	Bit2	Bit3	Bit4	Bit5	Bit6	Bit7
Reserved	Data-change	Quality-change	Data-update	Integrity	General-interrogation	0	0

Option field of report structure: The following bits indicate the stated option value when equal to 1:

MSB	Bit0	Bit1	Bit2	Bit3	Bit4	Bit5	Bit6	Bit7
MSB	Reserved	Sequence-number	Report-timestamp	Reason for inclusion	Data-set-name	Data-reference	Buffer-overflow	EntryID
LSB	Bit8	Bit9	Bit10	Bit11	Bit12	Bit13	Bit14	Bit15
LSB	Conf-revision	Segmen-tation	–	–	–	–	–	–

Quality element structure: The following bits indicate the stated quality value when equal to 1:

MSB	Bit0	Bit1	Bit2	Bit3	Bit4	Bit5	Bit6	Bit7
MSB	Validity: 00 = good 01 = invalid 10 = reserved 11 = questionable		Overflow	Out-of-range	Bad-reference	Oscillatory	Detected failure	Old-data
LSB	Bit8	Bit9	Bit10	Bit11	Bit12	Bit13	Bit14	Bit15
LSB	Inconsis-tent	Inaccurate	Source: 0 = process 1 = substituted	Test	Operator-blocked	–	–	–

CODED ENUM

Dbpos (double position) definition from IEC61850-8-1:

MSB	Bit0	Bit1	Bit2	Bit3	Bit4	Bit5	Bit6	Bit7
MSB	–	–	–	–	–	–	–	–
LSB	Bit8	Bit9	Bit10	Bit11	Bit12	Bit13	Bit14	Bit15
LSB	00 = intermediate state 01 = Off 10 = On 11 = Bad state		–	–	–	–	–	–

Custom Data Types

The 140 NOP 850 00 module also provides the following custom data types, which are used to support module DDTs:

Refer to the presentation of each custom data type elsewhere in this document for a description of its structure.