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2.4. Communication Interfaces
For data exchange with external units (i. e. computer or manual data reading terminal), the EPQS
meter has standard optical and electrical communication interfaces.
2.4.1. Optical Interface (D0)
This interface is used for the meter parameterisation and for transferring of data stored in the meter to
a data reading terminal or portable PC with a
QuadrCom
software installed in it. The optical interface
transfer protocol is IEC 62056-21compatible. The maximum transfer rate is 9600 bps.
2.4.2. Electrical communication Interface
This interface is used for the meter parameterisation and for data transfer via local network. The
electrical communication interface implements IEC 62056-31transfer protocol. The maximum data
transfer rate is 19200 bps. There can be following implementations of electrical interface:
•
RS 232;
•
RS 485;
•
Current loop interface (CL)
2.4.3. Auxiliary Communication Interface (optional)
The following auxiliary communication interface that operates independently from the optical and the
first electrical interfaces can be built in upon a request:
•
Current loop interface (CL2);
•
Electric interface RS 485 ;
•
Electric interface RS 232.
2.4.4. Interface Priorities
Communication through the optical interface D0 and the first electrical interface is provided by the
same single universal asynchronous receiver-transmitter unit (UART), so it is impossible to use both
interfaces for data transfer concurrently. The meter has strict software defined priorities for
communication interfaces, and a certain priority of one or another interface is determined by the
following rules:
•
Optical interface has higher priority than electrical;
•
If request is received through the optical interface while a communication session is going on
through the electrical interface, communication through electrical interface is interrupted, and
a request received through the optical interface is carried out. Communication through the
electrical interface is not interrupted only if an answer to a request is currently transmitted
through electrical interface. In that case communication is interrupted only after the answer
has been sent.
2.5. The Meter Inputs and Outputs
2.5.1. Optical LED Output (Red Light Emission Diodes)
The optical LED output is located on the front panel. It is used for the meter calibration and
verification. The LED emits light signals whose frequency corresponds to calculated electrical energy.
LED signals are generated by the meter CPU. Meter constant is the main parameter of the LED
output. The meter constant means a number of light signals emitted by LED for 1 kWh (1 kVAr or 1
kVA) of electrical energy.
The EPQS meter has two optical LED outputs. The meter constant is set by the manufacturer. Both
LED outputs can generate signals for active, reactive, or apparent electrical energy and the first
output (see Diagram 2-1) can additionally transmit the meter clock time signals in order to estimate
time count error. Table 2-3 lists LED output parameters.
Содержание EPQS
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