| CPC H02J 3/00 (2013.01) [H03K 5/22 (2013.01)] | 5 Claims |
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1. A coupler box, comprising:
a bus-side connector including: a ground (GND) terminal; an input voltage (VCC) terminal; a 1-5 volt (V) output terminal; and a dual-tone, multiple-frequency (DTMF) input terminal;
a field-device side connector, including: a GND terminal; a VCC output terminal; and a 1-5 V input terminal;
a first single-pole, single-throw (SPST) switch electrically disposed between the 1-5 V output terminal and the 1-5 V input terminal, wherein the first SPST switch is normally open;
a DTMF decoder having an input connected with the DTMF input terminal;
a dual in-line package (DIP) switch configured to set a binary value from 0000b to 1111b, inclusive; and
a comparator circuit having:
a first input connected with an output of the DTMF decoder;
a second input connected with the DIP switch; and
an output signal connected with a control input of the first SPST switch,
wherein the comparator circuit is configured to compare a decoded DTMF signal output by the DTMF decoder with the binary value set by the DIP switch, and
wherein the comparator circuit is further configured to assert its control output to close the first SPST switch when the decoded DTMF signal equals the binary value set by the DIP switch, thus electrically connecting the 1-5 V output terminal with the 1-5 V input terminal.
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