Hf Pulse Input With Automatic Conversion; Pulse Generator Connection - Honeywell EK280 Applications Manual

EK280

4.4 HF pulse input with automatic conversion

Pulses from a high-frequency pulse generator can be counted by the EK280 only when an external power
supply exists, i.e., not during battery operation. To ensure uninterrupted gas volume measurement, the
EK280 can be configured so that it switches to a low frequency pulse generator in the event of failure of the
external power supply.
When the power supply is functioning, volumes and loads (Vb, Vm, Qb, Qm) will be measured with the high
frequency pulse generator (priority input). In the event of failure of the high frequency pulse generator (e.g.,
due to failure of the external power supply), the EK280 automatically continues to measure with the low
frequency transmitted (fail safe input).

4.4.1 Pulse generator connection

Danger!
For EK280 with internal power supply, the mains voltage must be switched off before
opening the housing, ensure it is not turned back on and verify that there is no voltage.
LF Pulse
generator
(reed contact)
− Connect the gas meter's low frequency pulse generator (LF reed contact) to terminal "DE1" of the
EK280.
− Connect the gas meter's high frequency pulse generator (HF Namur) to terminal "DE2" of the
EK280. Respect polarity, i.e. connect the impulse generator's "+" to the "DE2 +" terminal and "-" with
"DE2 -".
− Release the inputs 1 and 2 (terminal "DE1" and "DE2") calibration seals.
Application Manual
DE1 DE2
+ - + -
+ -
Pulse generator
HF
(Namur)
27