• Gossen Metrawatt
  • Camille Bauer

EM402: What needs to be taken into consideration when connecting energy meters with pulse output to a PLC?

Energy meter pulse outputs are standardized in accordance with EN 62053-31 or DIN 43864 and are timed as follows:

In order to assure that the pulses can be detected with simple equipment, the ON state should be as long as possible - limitation is dictated by the selected pulse rate. At higher pulse rates and full load, the ON state must be short enough to ensure that the minimum time required for the OFF state is complied with.

If the shortest permissible ON state of 30 ms is selected and if this signal is fed to a controller’s digital input module, this may result in problems with pulse detection for some controllers with long cycle times and a large program volume. This can frequently be solved by selecting an ON state of 100 ms or longer.

In the case of over-dimensioned converters or networks, it may be necessary work with high pulse rates in favor of better resolution. Thanks to the reduced load, the pulse train is so minimal that the ON state can also be longer than would be possible due to limiting at full load. However, in applications of this sort it must be assured that the network load generally remains below the upper limit dictated by timing.

 

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