IEC 61107 is a protocol for local and remote reading of energy meters over a serial or telephone line. It was replaced by IEC 62056-21. In a SCADA master such as SYS600, reading is organized as a session: handshake, mode selection, password check, data reading and connection closing.
What IEC 61107 is
IEC 61107 is a communication protocol for reading energy meters. The standard that replaced it is IEC 62056-21. For that reason, in a new project it is worth identifying which of the two editions the meter uses before choosing the master.
This guide describes how an IEC 61107 master works in a SCADA, taking as an example the module of the ABB MicroSCADA Pro SYS600 version 9.4 system, documented in 2014. The general scheme is repeated in other systems: the SCADA builds a conversation with the meter, runs it and receives the responses.
For advanced metering with the modern meter protocol, see DLMS/COSEM Protocol: The Essentials.
Batch reading
In SYS600, communication with an IEC 61107 device is designed to be processed in batches. The SCADA application program first downloads a set of IEC 61107 messages to PC-NET (the communication unit) and then starts communication with the meter. During communication, PC-NET sends the downloaded messages to the device. The responses reach the SCADA as spontaneous messages to a bit-stream process object.
The interface is divided into two layers:
- Application layer: stores the downloaded messages before sending them to the meter. It is run by the PC-NET station process, of type ATR_DEVICE (code 27).
- Link layer: handles most of the interface functions. It is called the line process and the line type of the IEC 61107 protocol is IE_PROTOCOL (code 26).
PC-NET is transparent to IEC 61107 messages: it does not interpret them. It only adds the block check character (BCC) at the end of messages that begin with SOH or STX, and the serial number of each message at the start of the response, to identify it easily.
A communication session
A session is a sequence of messages that the SCADA sends to the meter, and it must include the handshake and the termination. The structure of the manual’s example is this:
| Step | What it does |
|---|---|
| Handshake | Establishes communication and selects the mode |
| Password check | Sends the meter password |
| Data reading | Messages with the requested data |
| Termination | Closes the connection with the meter |
Closing is mandatory within the session. When reading is done by telephone, the line does not hang up by itself either.
Reading over a telephone line
For remote meters, SYS600 uses its automatic dialing process (Autocaller) in the same way as for RTU lines. If the line AC attribute is active, the application dials the number by writing to the CN attribute, either before or after the message download. Two attributes control the connection:
- CL: indicates whether the connection has a time limit. The default value is 1, that is, with a limit. The manual considers it necessary on some radiotelephone lines.
- CT: maximum connection duration, from 0 to 600 seconds, with a default value of 120.
The telephone connection is cut if an empty string is written to CN or if the time limit is exceeded. PC-NET does not cut it automatically.
Serial line parameters
The line is associated with a serial port of the computer (by default, line 1 with COM1, line 2 with COM2) and with attributes such as baud rate and parity (none, odd or even). These values must match those of the meter; otherwise the messages are not understood. The line also has status attributes and error codes for diagnostics.
What to check when integrating a meter
- That the meter supports IEC 61107 and with which line parameters.
- That the session includes handshake, password, reading and termination.
- That baud rate and parity match at both ends.
- That there is a maximum connection time on telephone lines.
- That responses reach the correct SCADA process object.
We integrate your meters into the SCADA
We integrate meters and field devices into the SCADA with the protocol each one supports, from line configuration to verification of the readings on screen. Engineering is done remotely, worldwide; field work is done in Colombia, or elsewhere on request. See SCADA integration and gateways and write to us through contact.
Related guides
- DLMS/COSEM Protocol: The Essentials
- AMI Architecture: Meter, Concentrator and Head-End System
- Energy Meter and Multifunction Meter
- What Smart Metering (AMI) Is
- Signals That Do Not Reach the SCADA
Referencias
- IEC 61107, Electricity metering – Data exchange for meter reading, tariff and load control – Direct local data exchange (superseded by IEC 62056-21).
- IEC 62056-21, Electricity metering – Data exchange for meter reading, tariff and load control – Direct local data exchange.
- ABB, MicroSCADA Pro SYS600 9.4, IEC 61107 Master Protocol, Configuration Manual (1MRS758093).
Frequently asked questions
What is the difference between IEC 61107 and IEC 62056-21?
IEC 62056-21 replaced IEC 61107. If a meter supports only IEC 62056-21, consult the SCADA vendor, because the master described here is the IEC 61107 one.
Why must the session include a closing message?
Because the session must contain both the handshake and the termination messages. If a telephone modem is used, the line does not hang up by itself either: it is closed by writing an empty string to the call number attribute or when the maximum connection time runs out.
Who adds the BCC check character to the message?
In SYS600 it is added by PC-NET, the communication unit, at the end of messages that begin with SOH or STX. The application program only has to build the message.