GE P24DM Technical Manual Download

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6.2.2

INITIALISATION

Whenever the device has been powered up, or if the communication parameters have been changed a reset
command is required to initialize the communications. The device will respond to either of the two reset
commands; Reset CU or Reset FCB (Communication Unit or Frame Count Bit). The difference between the two
commands is that the Reset CU command will clear any unsent messages in the transmit buffer, whereas the
Reset FCB command does not delete any messages.

The device will respond to the reset command with an identification message ASDU 5. The Cause of Transmission
(COT) of this response will be either Reset CU or Reset FCB depending on the nature of the reset command. The
content of ASDU 5 is described in the IEC 60870-5-103 section of the Menu Database, available from General
Electric separately if required.

In addition to the above identification message, it will also produce a power up event.

6.2.3

TIME SYNCHRONISATION

The time and date can be set using the time synchronization feature of the IEC 60870-5-103 protocol. The device
will correct for the transmission delay as specified in IEC 60870-5-103. If the time synchronization message is sent
as a send/confirm message then the device will respond with a confirm message. A time synchronization Class 1
event will be generated/produced whether the time-synchronization message is sent as a send confirm or a
broadcast (send/no reply) message.

If the clock is being synchronized using the IRIG-B input then it will not be possible to set the device time using the
IEC 60870-5-103 interface. An attempt to set the time via the interface will cause the device to create an event
with the current date and time taken from the IRIG-B synchronized internal clock.

6.2.4

SPONTANEOUS EVENTS

Events are categorized using the following information:

●

Function type

●

Information Number

The IEC 60870-5-103 profile in the Menu Database contains a complete listing of all events produced by the
device.

6.2.5

GENERAL INTERROGATION (GI)

The GI request can be used to read the status of the device, the function numbers, and information numbers that
will be returned during the GI cycle. These are shown in the IEC 60870-5-103 profile in the Menu Database.

6.2.6

CYCLIC MEASUREMENTS

The device will produce measured values using ASDU 9 on a cyclical basis, this can be read from the device using a
Class 2 poll (note ADSU 3 is not used). The rate at which the device produces new measured values can be
controlled using the measurement period setting. This setting can be edited from the front panel menu or using
MiCOM S1 Agile. It is active immediately following a change.

The device transmits its measurands at 2.4 times the rated value of the analogue value.

6.2.7

COMMANDS

A list of the supported commands is contained in the Menu Database. The device will respond to other commands
with an ASDU 1, with a cause of transmission (COT) indicating ‘negative acknowledgement’.

6.2.8

TEST MODE

It is possible to disable the device output contacts to allow secondary injection testing to be performed using
either the front panel menu or the front serial port. The IEC 60870-5-103 standard interprets this as ‘test mode’. An

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