DEI PCX-7420 User manual

PCX-7420
Pulsed Current Source
Operation Manual
Directed Energy, Inc.
1609 Oakridge Dr., Suite 100, Fort Collins, CO 80525
[phone]
[e-mail]
www.directedenergy.com
Document #7650-0004, Rev. C2
© Copyright 2019, Directed Energy, Inc. All rights reserved.

Contents
Safety .............................................................................. 4
Quick Start Guide ........................................................... 5

Safety ............................................................................................................. 5

Requirements ................................................................................................ 5

Controlling the PCX-7420 From the Front Panel .......................................... 5

Controlling the PCX-7420 From a Computer ............................................... 6
Introduction .................................................................... 7

Description .................................................................................................... 7

Panel Layout .................................................................................................. 8

Front Panel Features ..................................................................................... 9

Rear Panel Features .................................................................................... 10

Accessories Included ................................................................................. 11
Operation ...................................................................... 13

Setup............................................................................................................ 13

Power Up ..................................................................................................... 13

Set the Output Current ................................................................................ 14

Set the Bias Current .................................................................................... 14

Set the Pulse Width ..................................................................................... 15

Set the Bias Width ....................................................................................... 15

Set the Trigger ............................................................................................. 16

Set the Frequency ....................................................................................... 17

View Information About the PCX-7420 ....................................................... 17

Save Settings ............................................................................................... 18

Recall Settings ............................................................................................ 19

Warnings and Faults .................................................................................... 20

View the Communication Settings .............................................................. 22

Power Down ................................................................................................. 23
Command Set ............................................................... 24
Warranty and Service .................................................. 30

Factory Service and Support ...................................................................... 30
CE Declaration .............................................................. 31

Page 4 of 32
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Safety
• Do not open the cover of PCX-7420. There are no user-serviceable parts inside.
Opening the cover exposes you to lethal shock and voids the factory warranty.
• Do not install, handle, or remove the output cable or laser diode while the PCX-
7420 is operating.
• The PCX-7420 can be triggered randomly by spurious transients. Always
assume it is possible to get an unexpected pulse at the output.
• Allow at least 10 minutes after power-down before handling the output cable
or laser diode.
• Do not use this device in a manner not specified by the manufacturer.
• Allow sufficient space around this device for air circulation. Cooling air enters
the front of the chassis and exits the back of the chassis.
• Take normal precautions to protect this device against liquid entry or
corrosive environments.
• Clean this device by wiping with a dry or damp cloth.
WARNING
Risk of lethal electric shock. Do not open the cabinet of this
device. Do not touch the output or laser diode while it is
operating. This device produces LETHAL levels of electric
current, both inside its cabinet and at its output.
DO NOT OPERATE THIS DEVICE UNLESS ANOTHER PERSON
CAPABLE OF RENDERING FIRST AID OR RESUSCITATION IS
PRESENT.
SAFE AND PROPER OPERATION OF THIS DEVICE IS THE
RESPONSIBILITY OF THE USER.
Directed Energy, Inc. (DEI) provides information on its products and
associated hazards, but it assumes no responsibility for the after-sale
operation and safety practices.

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Quick Start Guide

Safety
Follow the safety guidelines on Page 3. DO NOT PROCEED WITHOUT
UNDERSTANDING AND OBSERVING THESE GUIDELINES.

Requirements
Make sure the PCX-7420:
• Is connected with the proper cables and termination impedance
• Is powered up
• Has all faults cleared
• Has the rear enable and keyswitch enabled. Their icons should be green.

Controlling the PCX-7420 From the Front Panel
1. Disable the PCX-7420.
 If the ENABLE button on the front panel is illuminated, press the button to
disable the unit. The button goes dark.
2. Set the output current.
 Press the Output button on the touch screen.
 Press the encoder knob to set the resolution.
 Turn the encoder knob to set the output current from 0 mA to 15700 mA.
 Press the Done button.
3. Set the bias current.
 Press the Bias button on the touch screen.
 Press the encoder knob to set the resolution.
 Turn the encoder knob to set the bias current from 0 mA to 5800 mA.
 Press the Done button.
4. Set the trigger to internal or external as needed.
 Press the Trigger button on the touch screen.
 Press the Internal or External button to select the trigger.
5. Set the frequency.
 Press the Frequency button on the touch screen.
 Press the encoder knob to set the resolution.
 Turn the encoder knob to set the frequency from 40 Hz to 6000 Hz.
 Press the Done button.

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6. Set the pulse width.
 Press the Pulse Width button on the touch screen.
 Press the encoder knob to set the resolution.
 Turn the encoder knob to set the pulse width from 0.05 µs to 5000 µs.
 Press the Done button.
7. Set the bias pulse width.
 Press the Bias Width button on the touch screen.
 Press the encoder knob to set the resolution.
 Turn the encoder knob to set the bias pulse width from 0 µs to 25000 µs.
 Press the Done button.
8. Enable the PCX-7420.
 Press the ENABLE button on the front panel. The button illuminates.

Controlling the PCX-7420 From a Computer
1.
Disable the PCX-7420.
 Send the command “OUTPUT:DISABLE”.
2.
Set the main output current.
 Send the command “MAIN:CURRENT:SETPOINT n”. n = [0 to 15700]. Units
are milliamperes.
3.
Set the bias output current.
 Send the command “BIAS:CURRENT:SETPOINT n”. n = [0 to 5800]. Units
are milliamperes.
4.
Set the trigger to internal or external as needed.
 Send the command “TRIG:INTERNAL” or “TRIG:EXTERNAL”.
5.
Set the internal trigger frequency.
 Send the command “TRIG:INT:FREQ n”. n = [40 to 6000]. Units are hertz.
6.
Set the main pulse width.
 Send the command “TRIG:INT:MAIN:PULSEWIDTH n” n = [50 to 5000000].
Units are nanoseconds.
7.
Set the bias pulse width.
 Send the command “TRIG:INT:BIAS:PULSEWIDTH n” n = [0 to 25000000].
Units are nanoseconds.
8.
Enable the PCX-7420.
 Send the command “OUTPUT:ENABLE”.

Page 7 of 32
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Introduction

Description
The PCX-7420 is a pulsed current source designed to drive laser diodes, bars,
and arrays. It delivers current pulses from 0 A to 21.5 A with up to 375 W of total
output power. An internal trigger source provides pulse repetition frequencies from
40 Hz to 100 kHz. The external trigger function allows operation at frequencies
from single-shot to 1 MHz.
The bias current amplitude, the main output current amplitude, the bias pulse
width, the main pulse width, the trigger source, and the trigger frequency are
adjustable from the front panel touch screen or by computer control via RS232,
USB, or Ethernet interface.
The bias feature allows the PCX-7420 to deliver the current pulse in two steps.
The first step—the bias pulse—starts before the intended trigger time and is
adjusted to supply enough current to set the diode just below the lasing point. This
minimizes the diode’s response time to the main pulse. The bias pulse amplitude
is adjustable from 0 A to 5.8 A and its width is adjustable from 0 ms to 25 ms.
The main pulse current adds to the bias current and energizes the diode at the
intended time. The main pulse current is adjustable from 0 A to 15.7 A and its
width is adjustable from 50 ns to 5 ms.
Note: The total current output pulse is always the sum of the bias pulse current
and the main pulse current, even if the bias pulse width is set to zero. Consider
both the bias output current and the main output current when planning the total
output current.
The PCX-7420 can be triggered internally or externally, and it can be readily
synchronized with other devices via the Sync output signal on the front panel. The
input termination impedance for both the external trigger and the external bias
trigger is selectable for either 50 Ω or 10000 Ω. The Sync signal logic amplitude is
0 V and +5 V. The rising edge corresponds to the rising edge of the main output
current pulse. The delay between the sync output signal and the main output
current pulse is 5 ns to 15 ns.

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
Panel Layout
All features of the front and rear panel are labeled. Their functions are covered in
the next section.

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
Front Panel Features
LOCAL Button
Returns the PCX-7420 to front-panel control during computer control. Illuminates red
during power-up initialization. Flashes red during a fault.
ENABLE Button
Toggles the PCX-7420 between enabled and disabled. Illuminates green when the
unit is enabled. Illuminates solid green, then flashes green during power-up
initialization.
Touch Screen
Provides a graphic user interface and front-panel touch control for most of the
functions of the PCX-7420.
Encoder Knob
Turn to change a value. Push to cycle through the resolutions (increments of value
change).
Keyswitch
ON enables the PCX-7420. OFF disables the PCX-7420.
Sync Output
A BNC connector that provides synchronization pulses to external devices. The sync
pulse is triggered by the leading edge of the output current pulse.
External Trigger Input
A BNC connector that accepts trigger pulses from an external source. Its input
impedance can be set to either 50 Ω or 10 kΩ.
External Bias Input
A BNC connector that accepts bias trigger pulses from an external source. Its input
impedance can be set to either 50 Ω or 10 kΩ.

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
Rear Panel Features
Output
A socket that accepts the factory-supplied output cable and provides the generated
current pulses. DO NOT TOUCH any part of this cable while the PCX-7420 is powered
up. Please review the Safety section on Page 3.
Note: Absence of a properly-installed output cable disables the output and creates a
rear enable fault.
Rear Enable
A BNC connector that accepts either an external dry-contact closure or the factory-
supplied shorting BNC plug. Closed contacts, or use of the shorting plug, enables the
output. Open contacts, or removal of the shorting plug, disables the output and creates
a rear enable fault.
IMON Output
A BNC connector that provides a connection to an oscilloscope. The signal is a
voltage that represents the current output. Scaling is 36 mV / 1 A into 50 Ω
Ethernet Cable Connector
Communicates with an external computer through an Ethernet cable.
USB Cable Connector
Communicates with an external computer through a USB cable.
RS232 Cable Connector
Communicates with an external computer through an RS232 null cable.
Power Cable Connector
Accepts a standard grounding equipment power cable.
Fuse Holder
Houses two AC power fuses.
On-Off Switch
Powers the PCX-7420 ON and OFF.

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
Accessories Included
AC Power Cable
A factory-supplied standard computer-style power cord, with NEMA C14 and NEMA
5-15R connectors.
Shorting BNC Plug
Attaches to the Rear Enable BNC connector on the rear panel. It takes the place of
closed contacts and enables the output.
Keyswitch Keys
For the front-panel On-Off keyswitch. On enables the output.
Output Cable
A factory-supplied cable that provides high current pulses to external devices. A DB-
37 male connector fits the socket on the rear panel of the PCX-7420; a DB-37 female
connector is on the user end.
Output Cable Connector Pinouts
The male DB-37 connector interfaces with the instrument and has the following pinout:
 Pins 1 through 16: positive (+) output
 Pins 20 through 35: negative (‒) output
 Pins 17, 36, 37: no connection
 Pins 18 and 19: connected together to satisfy interlock requirement
The female DB-37 connector interfaces with the customer’s laser diode PC board and
AC
Power
Cable
Cable
Shorting
BNC Plug
Keyswitch
Keys

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has the following pinout:
 Pins 1 through 16: positive (+) connection (to laser diode anode)
 Pins 20 through 35: negative (‒) connection (to laser diode cathode)
 Pins 17, 18, 19, 36, 37: no connection
Interlock
The DEI instrument requires that pins 18 and 19 of the male DB-37 be connected to
satisfy an interlock that determines whether the output cable is present. If this
connection is not detected the instrument will not be enabled.
Output Cable Diagram
The diagram below depicts the male and female connectors and their pinouts.

Page 13 of 32
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Tools
Button
brings up
Settings
Menu
Trigger
Button
to
switch internal/
external
trigger
Frequency
Button
to set internal
trigger frequency
Pulse Width
Button to set
output pulse width
Bias
Width
Button
to
set bias pulse width
Keyswitch
Status Icon
Rear
Enable
Status Icon
Temperature
Status Icon
Operation

Setup
1.
Make sure the PCX-7420 has been OFF for at least ten minutes.
2.
Make sure the polarity of the diode connection is correct. If necessary, review the
output cable pinout in the Specifications section.
3.
Make the other connections as necessary: External Trigger, External Bias, Sync,
IMON, Rear Enable, and the connection to the computer.
4.
Connect the power cable.

Power Up
1.
Turn the power switch ON (I).
 The unit plays a tune and the ENABLE button flashes green as the unit
initializes.
 The PCX-7420 powers up in Internal Trigger mode and the Home screen
appears. The main features of the Home screen are shown below.
2.
Turn the keyswitch ON.
Help
Button
describes
other icons
Output
Button to
set output
current
Output
Button to
set output
current
Status
Icons:
Green
=
OK
or
enabled.
Red
=
Fault
or
disabled.
Numerical displays show the current settings for all parameters.

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
Set the Output Current
MAIN:CURRENT:SETPOINT?
MAIN:CURRENT:SETPOINT n
1.
On the Home screen, press the Output
button.
2.
The Set Output Current screen appears. Press
the encoder knob to select a resolution:
x0.001, x0.010, x0.100, or x1.000.
3.
Turn the encoder knob to adjust the output
current. The range is 0 A to 15.7 A.
4.
On the screen, press the Done button.

Set the Bias Current
BIAS:CURRENT:SETPOINT?
BIAS:CURRENT:SETPOINT n
1.
On the Home screen, press the Bias button.
2.
The Set Bias Current screen appears. Press
the encoder knob to select a resolution:
x0.001, x0.010, x0.100, or x1.000.
3.
Turn the encoder knob to adjust the bias
current. The range is 0 A to 5.8 A.
4.
On the screen, press the Done button.

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
Set the Pulse Width
TRIG:INT:MAIN:PULSEWIDTH?
TRIG:INT:MAIN:PULSEWIDTH n
1.
On the Home screen, press the Pulse Width
button.
2.
The Set Pulse Width screen appears. Press
the encoder knob to select a resolution:
x0.025, x0.100, x1, x100, or x1000.
3.
Turn the encoder knob to adjust the pulse
width. The range is 0.05 µs to 5000 µs.
4.
On the screen, press the Done button.

Set the Bias Width
TRIG:INT:BIAS:PULSEWIDTH?
TRIG:INT:BIAS:PULSEWIDTH n
1.
On the Home screen, press the Bias Width
button.
2.
The Set Bias Width screen appears. Press the
encoder knob to select a resolution: x0.025,
x0.100, x1, x100, or x1000.
3.
Turn the encoder knob to adjust the bias width.
The range is 0 µs to 25000 µs.
4.
On the screen, press the Done button.

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
Set the Trigger
Set the Source
TRIG:INTERNAL
TRIG:EXTERNAL
NOTE:
If you have just powered up the PCX-7420, the
unit is in Internal Trigger mode.
1.
On the Home screen, press the gray Trigger
button.
2.
The Select Trigger screen appears. Press the
button for the desired trigger mode.
 If you select Internal Trigger, the Home
screen reappears. Set the Frequency.
 If you select External Trigger, the Set
Termination screen appears. Set the
Termination if necessary.
OR
Set the Termination
TRIG:EXT:TERM?
TRIG:EXT:TERM n
 If you selected External Trigger, the
External Trigger Home screen appears.
Press a Termination button to set the
termination of the external trigger input to 50
Ω or 10 kΩ.

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
Set the Frequency
TRIG:INT:FREQ?
TRIG:INT:FREQ n
1.
From the Home screen, press the Frequency
button.
2.
The Set Frequency screen appears. Press the
encoder knob to change the resolution: x100,
x1000, or x10000.
3.
Turn the encoder knob to adjust the trigger
frequency. The range is 40 Hz to 100000 Hz.
4.
On the screen, press the Done button. The
Home screen reappears.

View Information About the PCX-7420
*IDN?
1.
On the Home screen, press the tools button.
2.
The Settings screen appears. Press the About
button.
3.
The About screen appears. View the model
number, serial number, manufacture date, and
firmware revision level.
4.
Press the upper left icon button to return to the
Home screen.

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
Save Settings
*SAVE n
1.
On the Home screen, press the tools button.
2.
The Settings screen appears. Press the Save
Settings button.
3.
The Save screen appears. Press the button for
one of the four locations to which you want to
save the settings.
NOTE:
Saving to a location overwrites any data
previously stored at that location.
4.
A progress indicator appears. When it is
finished, press the upper left icon button to
return to the Home screen.

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
Recall Settings
*RECALL n
1.
On the Home screen, press the tools button.
2.
The Settings screen appears. Press the Recall
Settings button.
3.
The Recall screen appears. Press the button
for one of the four locations from which you
want to recall the settings.
4.
A progress indicator appears. When it is
finished, press the upper left icon button to
return to the Home screen.

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
Warnings and Faults
All faults disable the PCX-7420. To continue after clearing a fault, you must send
an “OUTPUT:ENABLE” command from the computer or press the ENABLE button
on the front panel.
Red Keyswitch Status Icon
STATUS:KEYSWITCH?
 The keyswitch was OFF at power-up, or it was
turned OFF during disabled operation.
 This is also the display after clearing a
keyswitch hardware warning or a keyswitch
fault.
 Turn the keyswitch ON to continue.
Keyswitch Hardware Warning
FAULT:CLEAR:ALL
 The user attempted to enable the PCX-7420
while the keyswitch was OFF.
 On the screen, press the Clear Warning
button.
 The Home screen appears with a red
keyswitch status icon.
 Turn the keyswitch ON to continue.
Keyswitch Fault
FAULT:CLEAR:ALL
 The keyswitch was turned OFF during enabled
operation.
 On the screen, press the Clear Fault button.
 The Home screen appears with a red
keyswitch status icon.
 Turn the keyswitch ON to continue.