EDI 242L User manual

THIS MANUAL CONTAINS TECHNICAL INFORMATION FOR
THE MODEL 242L AND 244L SERIES DC ISOLATOR
REVISION: OCTOBER 2015
pn 888-2420-002
Model 242L / 244L
DC Isolator Unit
Operations Manual

THE MODEL 242L/244L SERIES IS DESIGNED AND MANUFACTURED IN THE USA BY
EBERLE DESIGN INC.
PHOENIX, ARIZONA
AN ISO 9001:2015 REGISTERED COMPANY
INFORMATION CONTAINED HEREIN IS PROPRIETARY TECHNICAL INFORMATION
OF EBERLE DESIGN INC. PUBLICATION, REPRODUCTION OR USE IN WHOLE OR
PART IS NOT PERMITTED EXCEPT UNDER TERMS AGREED UPON IN WRITING.
U.S. PATENT NO. 7,855,893
©COPYRIGHT 2015 EDI.

Table of Contents
1.1 Glossary................................................................................................................. 1
1.2 General Description................................................................................................ 1
1.3 General Characteristics.......................................................................................... 1
1.4 Installation and Adjustments................................................................................... 2
1.4.1 Minimum Output Pulse.................................................................................. 2
1.4.2 Input Polarity................................................................................................. 2
1.5 Theory of Operation ............................................................................................... 2
1.5.1 System Description....................................................................................... 2
1.5.2 Input Circuit................................................................................................... 3
1.5.3 MCU Circuit .................................................................................................. 3
1.5.4 Output Circuit................................................................................................ 3
1.5.5 Display and Switch Circuit............................................................................. 3
1.5.6 Power Supply Circuit..................................................................................... 3
1.6 Maintenance .......................................................................................................... 3
1.6.1 Trouble Analysis ........................................................................................... 3
1.6.2 Trouble Shooting Sequence.......................................................................... 4
1.7 Specifications......................................................................................................... 4
1.7.1 Mechanical.................................................................................................... 4
1.7.2 Environmental............................................................................................... 4
1.7.3 Electrical....................................................................................................... 4
1.7.4 Timing........................................................................................................... 5
1.7.5 242L Connections......................................................................................... 5
1.7.6 244L Connections......................................................................................... 5

Eberle Design Inc. Page 1
1.1 GLOSSARY
A - Ampere
oC - Celsius
Component - Any electrical or electronic device
DC - Direct Current
Firmware –Program code embedded into a microcontroller unit
Hz - Hertz
IC - Integrated Circuit
Jumper - A means of connecting/disconnecting two or more conductive by
soldering/desoldering a conductive wire or by PCB post jumper
LED - Light Emitting Diode
LOGIC - Negative Logic Convention (Ground True) State
mA - milliAmpere
ms - millisecond
MCU - Micro Controller Unit or microcontroller unit
MOV - Metal Oxide Varistor
Opto-coupler –An integrated circuit that provides electrical isolation
PCB - Printed Circuit Board
RMS - Root-Mean-Square
s –second
Schmitt Circuit –a circuit that provides hysterisis in the threshold
SW –Switch
uF - microfarad
VAC - Voltage Alternating Current
VDC - Voltage Direct Current
1.2 GENERAL DESCRIPTION
The Model 242L is a dual channel DC Isolator unit designed to meet Caltrans specifications
TEES 2009 including Errata #2 (December 2014). The Model 244L is a quad channel DC
Isolator unit in a half-width form factor. These isolator units occupy one position of a 33X
style standard input file. The isolator unit card incorporates a double-sided 44 pin edge
connector for the connection of power, input, and output signals. Each channel has individual
front panel controls for testing the operational mode, and high intensity front panel LEDs
which are used to indicate the output state. Outputs are optically-isolated solid-state
transistors. The Model 242L and 244L are powered from the 24VDC Cabinet Power Supply
and do not require AC Line.
While the Model 244L is interchangeable with the Model 242L, note that the Model 244L can
only be installed in the even numbered slots of a standard Input Assembly. The Model 244L
half-width form factor is primarily intended for use in rack assemblies designed for double
density (four channel half-width) detector/isolator units.
1.3 GENERAL CHARACTERISTICS
Each channel of the Model 242L/244L provides input hysterisis and digital filtering to qualify
the input signal. An input signal must meet the minimum pulse requirements specified in
section 1.7.4 in order to produce a valid output. The output pulse width for both channels can
be set to 100 milliseconds minimum by installing jumper “100ms” (J4-A).
Both the input and output circuits have been designed formaximum protectionfrom electrical
transients. The inputs have been designed to withstand the discharge of a 10 uF capacitor
charged to +/- 1000 Vdc directly across the input pins, and a discharge of a 10 uF capacitor
charged to +/- 2000 Vdc applied through a source impedance of 5 ohms across the input
pins or to Equipment Ground. The outputs are protected by a transient clamp diode.

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The Model 242L/244L handle assembly is made of GE LexanTM 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). The input polarity of Channel 3 can be set to
invert by installing a jumper into the “CH3 POL” (J4-C). The input polarity of Channel 4 can
be set to invert by installing a jumper into the “CH4 POL” (J4-D).
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 (244L) has two (four) 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”.

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The Model 242L/244L operating voltage is generated by a high efficiency isolated switching
power supply. The resulting bias voltage supplied to the Input circuits is electrically isolated
from both 24VDC Logic Ground and AC Line Neutral. The VDD supply for the microcontroller
and display elements results from a post regulated 5 Vdc.
1.5.2 INPUT CIRCUIT
Resistors R21, R7, R8, R25, and R19 (R22, R9, R3, R26, and R20) provide the input bias
and voltage scaling circuit. The resulting voltage at U20.3 (U20.4) is then processed by the
microcontroller U20. Gas tube CR2 (CR3) and diode CR 14 (CR16) provides input electrical
transient protection.
1.5.3 MCU CIRCUIT
The microcontroller U20 processes the input voltages to perform the voltage threshold and
pulse width filtering functions. All signal processing is performed in the digital domain and
controlled by firmware embedded in the microcontroller. This unit does not rely on analog
delay, pulse, or comparator circuits for processing the input signals.
1.5.4 OUTPUT CIRCUIT
The output driver Q7 (Q8) is isolated from both the AC Mains and the internal GND reference
of the Model 242L by opto-couplers U8 (U9). CR9 (CR6) provides electrical transient
protection for the output driver Q7 (Q8).
1.5.5 DISPLAY AND SWITCH CIRCUIT
The LED indicator DS1 (DS3) forthe channel output is driven directly from the microcontroller
U20. The input TEST switch SW1 (SW3) can be used to force the input state to the active
status.
1.5.6 POWER SUPPLY CIRCUIT
The main power supply is a fully isolated switching design. The cabinet 24VDC input voltage
is used to drive switching controller U18. The transformer T1 is used by controller U18 to
generate the isolated and regulated 19 VDC input bias voltage VCC that drives the input
circuits. The opto-coupler U21 and reference U25 provide the closed loop feedback to the
power supply controller U18 for regulation.
A second regulator U26 generates the 5.0 Vdc internal supply voltage VDD used by the
processor circuit from the 19 VDC bias. Inductor L2, C29, C31, and C24 filter the regulator
U26 output to provide clean VDD to the processor.
1.6 MAINTENANCE
The Model 242L/244L requires no adjustments or preventive maintenance.
1.6.1 TROUBLE ANALYSIS
The following list should be used to trouble-shoot the Model 242L/244L installation. If the
Model 242L/244L unit itself is suspect, see Section 1.6.2 for a complete internal testing
sequence.
a. Neither channel responds to DC inputs
a. Power supply fault
The Model 242L/244L requires a nominal 24 Vdc input voltage. The unit will
operate at voltages as low as 10.8 Vdc, however, an input voltage below this may
result in the unit entering a reset state. In this case, the unit will appear to be non-
functional.
b. Channel does not detect all inputs

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a. Input voltage or pulse width does not meet the requirements of section 1.7.3 or
1.7.4.
Verify that the DC input voltage level is less than the DC Inputs True specification.
Verify that the DC input pulse width is greater than the Input Pulse Width Accept
specification.
1.6.2 TROUBLE SHOOTING SEQUENCE
Apply 24 Vdc nominal power to DC POWER pin J1-B referenced to LOGIC GROUND pin J1-
A. Connect a jumper circuit to the DC inputs J1-D (J1-J) and J1-E (J1-K) to simulate the
closure of the input contacts. The following signal measurements are referenced to test point
CH1 (CH2).
NOTE: internal test point “GND” is isolated from Logic Ground. Care should be exercised in
probing internal test points.
a. Input Bias Power Supply VCC
Voltage at test point VCC should be 19 1 Vdc with respect to GND.
Possible component faults are: controller U18, CR12, R14, transformer T1, CR30,
reference U25, or opto-coupler U21.
b. Regulated Power Supply VDD
Voltage at test point VDD should be 5 0.2 Vdc with respect to GND.
Possible component faults are: voltage regulator U26, inductor L2, diode CR29.
c. Microcontroller
Possible components at fault are: microcontroller U20.
d. Output Circuit
Output signals are processed by the microcontroller U20 and appear at U20.10
(U20.9) and on the display LEDs but are not appearing at the output pins.
Possible components at fault are: opto-coupler U8 (U9), transistor Q7 (Q8).
1.7 SPECIFICATIONS
1.7.1 MECHANICAL
Height........................................................................................................4.50 inches
Width (242L)............................................................................................... 1.2 inches
Width (244L)............................................................................................... 1.2 inches
Depth (excluding handle).........................................................................6.875 inches
1.7.2 ENVIRONMENTAL
Storage Temperature Range................................................................. -45 to +85 oC
Operating Temperature Range.............................................................. -34 to +74 oC
Humidity Range (non-condensing)...................................................0 to 95% Relative
1.7.3 ELECTRICAL
DC Supply Voltage Minimum.........................................................................10.8 Vdc
DC Supply Voltage Maximum........................................................................28.0 Vdc
DC Supply Power Maximum.........................................................................2.0 Watts
DC Inputs
True (low)................................................................................... less than 8 Vdc
False (high) ..........................................................................greater than 12 Vdc
Optically Isolated Solid State Outputs
True (low, 50 mA).....................................................................less than 1.5 Vdc
False (high) ..........................................................................greater than 16 Vdc
Maximum Leakage Current (high).................................................less than 1 uA
Maximum Current..................................................................................... 50 mA
Collector Voltage Maximum......................................................................50 Vdc

Eberle Design Inc. Page 5
1.7.4 TIMING
Input Pulse Width Reject ......................................................................less than 5 ms
Input Pulse Width Accept...............................................................greater than 10 ms
1.7.5 242L CONNECTIONS
Edge Connector mates with connector type Cinch 50-44A-30
PIN
FUNCTION
A
Logic Ground
B
DC Supply
D
Input CH 1
E
Input CH 1 Common
F
CH 1 Output Collector
H
CH 1 Output Emitter
J
Input CH 2
K
Input CH 2 Common
L
Equipment Ground
W
CH 2 Output Collector
X
CH 2 Output Emitter
1.7.6 244L CONNECTIONS
Edge Connector mates with connector type Cinch 50-44A-30
PIN
FUNCTION
A
Logic Ground
B
DC Supply
D
Input CH 1
E
Input CH 1 Common
F
CH 1 Output Collector
H
CH 1 Output Emitter
J
Input CH 2
K
Input CH 2 Common
L
Equipment Ground
P
Input CH 3
R
Input CH 3 Common
S
CH 3 Output Collector
T
CH 3 Output Emitter
U
Input CH 4
V
Input CH 4 Common
W
CH 2 Output Collector
X
CH 2 Output Emitter
Y
CH 4 Output Collector
Z
CH 4 Output Emitter