Model 242L Operations Manual
Eberle Design Inc.
Page 2
The Model 242L handle assembly is made of GE Lexan
TM
Type 121, which is a super durable
polycarbonate resin. The design of this assembly strengthens and protects the whole PCB assembly
much better than conventional metal face plates.
1.4 INSTALLATION AND ADJUSTMENTS
Installation of the unit consists of plugging into the appropriate slot of the Input File and connecting the
assigned inputs to the proper cabinet terminals. The edge connector is keyed to prevent incorrect
installation. Following power-up, a front panel LED test will illuminate both OUT indicators for two
seconds.
1.4.1 MINIMUM OUTPUT PULSE
If desired, the output pulse width for both channels can be set to 100 milliseconds minimum by installing
jumper
“100ms” (J4-A).
1.4.2 INPUT POLARITY
The polarity of the input can be inverted such that a closed contact input is False and an open contact
input is True. The input polarity of Channel 1 can be set to invert by installing a jumper into the
“CH1
POL” (J4-B). The input polarity of Channel 2 can be set to invert by installing a jumper into the “CH2
POL” (J4-C).
1.5 THEORY OF OPERATION
Reference designators shown are for Channel 1. Reference designators for Channel 2 are shown in
parenthesis.
1.5.1 SYSTEM DESCRIPTION
The sensor circuitry can be broken down into seven major blocks. Each
“Input Circuit” block contains
the electrical transient devices and the input biasing circuit. Although the Model 242L has two DC
inputs, a single digital processing section is used to process both inputs.
The microcontroller unit
“MCU” Block provides the input voltage threshold and input pulse width filtering
function on both channel 1 and channel 2 DC input circuits.
The MCU then controls the OUTPUT and DISPLAY blocks appropriately. The TEST switches can be
used to force the input to the True state. If the TEST switch is in the ON (locked) or MOM (momentary)
position it will force the output to the asserted (True) state regardless of the input circuit state. The
TEST switches are processed through the MCU for pulse width input and output requirements.
Valid output calls are made via optically isolated solid state transistors. Output calls are indicated on
the front panel by means of red LEDs
labeled “OUT”.
