Aba Track Ii Clock & Data Reader; Aba Track Ii Specifications - Essex Electronics K1 Series Installation Instructions Manual

ABA Track II Clock & Data Reader

ABA Track II Specifications

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GREEN <Clock> goes low to clock in data. WHITE <Data> output
is determined by ORANGE. If ORANGE is low, then Data output is
inverted. If ORANGE is high, then Data output is normal.
Clock and Data signals are open collector outputs with 2.2K pull-ups
to the internal +5v. Clock Pulse is sent at 200 usec. Interbit delay is
750 usec. An annunciator beeps with each key press. An output is
generated with each key press which can be used to drive a CCTV
or Security Light. Located through the BLUE wire (see Connector
Wiring), this is an open collector output capable of sinking 1/4 A with
a 30 second on time.
Each key press generates an ABA Data Format as follows:
1. Each character is sent as a 5 bit value. The first 4 bits of each
character are the data value LSB first. The last bit of each char-
acter is an odd parity bit. The first four 0's are sent as lead in.
2. The Start Character is sent next. The Start Character is a "B"
with odd parity bit. Each entered character is now sent as 5 bits
per character with odd parity and LSB first. There can be up to a
max of 12 characters.
3. After all the keyed in characters have been sent, then the End
Sentinel is sent. The End Sentinel is an "F" with odd parity.
Next the LRC code is sent as a 5 bit character with odd parity.
The LRC code is created by XORing all of the characters sent
including the Start Characters, the Digit Characters and the End
Sentinel. It is calculated as a 4 bit value from XORing all the
previous characters. Its value is then sent as a 5 bit value, the
5th bit being its own odd parity.
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