TSI Instruments SIZER 3321 User Manual

AERODYNAMIC PARTICLE

SIZER® SPECTROMETER

MODEL 3321

USER’S MANUAL

P/N 1930092, REVISION H

SEPTEMBER 2013

AERODYNAMIC PARTICLE

SIZER® SPECTROMETER

MODEL 3321

USER’S MANUAL

Product Overview

1

Unpacking and
System Setup

2

Description of the
APS™ Spectrometer

3

APS™ Spectrometer
Operations

4

Theory of Operation

5

Contacting Customer
Service

6

Appendixes

Manual History

The following is a manual history of the Model 3321 Aerodynamic Particle
Sizer® Spectrometer (Part Number 1930092).

Revision Date

Preliminary March 1997
Preliminary 2 September 1997
Final November 1997
October 1998
A July 2000
B December 2001
C January 2002
D August 2002
E January 2004
F July 2009
G February 2012
H September 2013

ii Model 3321 Aerodynamic Particle Sizer® Spectrometer

Part Number

1930092 / Revision H / September 2013

Copyright

©TSI Incorporated / 1997–2013 / All rights reserved.

Address

TSI Incorporated / 500 Cardigan Road / Shoreview, MN 55126 / USA

Email Address

[e-mail]

World Wide Web Site

www.tsi.com

Fax No.

[phone]

Limitation of Warranty
and Liability

(effective June 2011)

(For country-specific terms and conditions outside of the USA, please visit www.tsi.com.)
Seller warrants the goods sold hereunder, under normal use and service as described in the

operator's manual, shall be free from defects in workmanship and material for 12 months, or if
less, the length of time specified in the operator's manual, from the date of shipment to the
customer. This warranty period is inclusive of any statutory warranty. This limited warranty is
subject to the following exclusions and exceptions:

Warranty

a. Hot-wire or hot-film sensors used with research anemometers, and certain other components

when indicated in specifications, are warranted for 90 days from the date of shipment;
b. Pumps are warranted for hours of operation as set forth in product or operator’s manuals;
c. Parts repaired or replaced as a result of repair services are warranted to be free from defects

in workmanship and material, under normal use, for 90 days from the date of shipment;
d. Seller does not provide any warranty on finished goods manufactured by others or on any

fuses, batteries or other consumable materials. Only the original manufacturer's warranty

applies;
e. Unless specifically authorized in a separate writing by Seller, Seller makes no warranty with

respect to, and shall have no liability in connection with, goods which are incorporated into

other products or equipment, or which are modified by any person other than Seller.
The foregoing is IN LIEU OF all other warranties and is subject to the LIMITATIONS stated

herein. NO OTHER EXPRESS OR IMPLIED WARRANTY OF FITNESS FOR PARTICULAR

PURPOSE OR MERCHANTABILITY IS MADE. WITH RESPECT TO SELLER’S BREACH OF
THE IMPLIED WARRANTY AGAINST INFRINGEMENT, SAID WARRANTY IS LIMITED TO
CLAIMS OF DIRECT INFRINGEMENT AND EXCLUDES CLAIMS OF CONTRIBUTORY OR

INDUCED INFRINGEMENTS. BUYER’S EXCLUSIVE REMEDY SHALL BE THE RETURN OF

THE PURCHASE PRICE DISCOUNTED FOR REASONABLE WEAR AND TEAR OR AT
SELLER’S OPTION REPLACEMENT OF THE GOODS WITH NON-INFRINGING GOODS.

TO THE EXTENT PERMITTED BY LAW, THE EXCLUSIVE REMEDY OF THE USER OR
BUYER, AND THE LIMIT OF SELLER'S LIABILITY FOR ANY AND ALL LOSSES, INJURIES,
OR DAMAGES CONCERNING THE GOODS (INCLUDING CLAIMS BASED ON CONTRACT,
NEGLIGENCE, TORT, STRICT LIABILITY OR OTHERWISE) SHALL BE THE RETURN OF
GOODS TO SELLER AND THE REFUND OF THE PURCHASE PRICE, OR, AT THE OPTION
OF SELLER, THE REPAIR OR REPLACEMENT OF THE GOODS. IN THE CASE OF
SOFTWARE, SELLER WILL REPAIR OR REPLACE DEFECTIVE SOFTWARE OR IF UNABLE
TO DO SO, WILL REFUND THE PURCHASE PRICE OF THE SOFTWARE. IN NO EVENT
SHALL SELLER BE LIABLE FOR LOST PROFITS OR ANY SPECIAL, CONSEQUENTIAL OR
INCIDENTAL DAMAGES. SELLER SHALL NOT BE RESPONSIBLE FOR INSTALLATION,
DISMANTLING OR REINSTALLATION COSTS OR CHARGES. No Action, regardless of form,
may be brought against Seller more than 12 months after a cause of action has accrued. The
goods returned under warranty to Seller's factory shall be at Buyer's risk of loss, and will be
returned, if at all, at Seller's risk of loss.

Buyer and all users are deemed to have accepted this LIMITATION OF WARRANTY AND
LIABILITY, which contains the complete and exclusive limited warranty of Seller. This
LIMITATION OF WARRANTY AND LIABILITY may not be amended, modified or its terms
waived, except by writing signed by an Officer of Seller.

iii

Service Policy

Knowing that inoperative or defective instruments are as detrimental to TSI as they are to our
customers, our service policy is designed to give prompt attention to any problems. If any mal­function is discovered, please contact your nearest sales office or representative, or call TSI
at 1-800-874-2811- (USA) or [phone].

Trademarks

TSI, TSI logo, Aerodynamic Particle Sizer, and Aerosol Instrument Manager are registered
trademarks of TSI Incorporated. APS is a trademark of TSI Incorporated.

Microsoft, Windows, are registered trademarks of Microsoft Corporation.
Swagelok is a registered trademark of Swagelok® Companies, Solon, Ohio.

iv Model 3321 Aerodynamic Particle Sizer® Spectrometer

W A R N I N G

The use of controls, adjustments, or procedures other than those
specified in this manual may result in exposure to hazardous optical
radiation.

W A R N I N G

High voltage is accessible in several locations within this instrument.
Make sure you unplug the power source before removing the cover or
performing maintenance procedures.

Safety

This section gives instructions to promote safe and proper handling of the
Model 3321 Aerodynamic Particle Sizer® Spectrometer.

There are no user serviceable parts inside the instrument. Refer all repair
and maintenance to a qualified technician. All maintenance and repair
information in this manual is included for use by a qualified technician.

The Model 3321 Aerodynamic Particle Sizer® spectrometer is a Class I
laser-based instrument. During normal operation, you will not be exposed
to laser radiation. However, you must take certain precautions or you may
expose yourself to hazardous radiation in the form of intense, focused,
visible light. Exposure to this light may cause blindness.

Take these precautions:

Labels

 Do not remove any parts from the APS™ spectrometer unless you are

specifically told to do so in this manual.

 Do not remove the APS™ housing or covers while power is supplied to

the instrument.

The Model 3321 has eight labels as shown in Figure 1.

1. Laser Safety Information Label (back panel)

2. Serial Number Label (back panel)

3. Customer Service Label (back panel)

4. Danger High Voltage Label (Power Entry Module)

5. Danger High Voltage Label (Display Inverter)

6. Danger Laser Radiation (Optics Assembly)

v

7. Ground Label (inside bottom)

8. Danger High Voltage Label (Analog PC-Board)

Figure 1

Location of Warning and Information Labels

vi Model 3321 Aerodynamic Particle Sizer® Spectrometer

Description of Caution/ Warning Symbols

C a u t i o n

Caution means be careful. It means if you do not follow the procedures

prescribed in this manual you may do something that might result in
equipment damage, or you might have to take something apart and start
over again. It also indicates that important information about the operation
and maintenance of this instrument is included.

W A R N I N G

Warning means that unsafe use of the instrument could result in serious

injury to you or cause irrevocable damage to the instrument. Follow the
procedures prescribed in this manual to use the instrument safely.

Warns you that uninsulated voltage within the instrument may
have sufficient magnitude to cause electric shock. Therefore,
it is dangerous to make any contact with any part inside the
instrument.

Warns you that the instrument contains a laser and that
important information about its safe operation and
maintenance is included. Therefore, you should read the
manual carefully to avoid any exposure to hazardous laser
radiation.

Warns you that the instrument is susceptible to electro-static
discharge (ESD) and ESD protection procedures should be
followed to avoid damage.

Indicates the connector is connected to earth ground and
cabinet ground.

The following symbols and an appropriate caution/warning statement are
used throughout the manual and on the Model 3321 to draw attention to
any steps that require you to take cautionary measures when working with
the Model 3321:

Caution

Warning

Caution or Warning Symbols

The following symbols may accompany cautions and warnings to indicate
the nature and consequences of hazards:

Safety vii

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viii Model 3321 Aerodynamic Particle Sizer® Spectrometer

Contents

Manual History .......................................................................................... ii

Warranty ................................................................................................... iii

Safety ......................................................................................................... v

Labels ....................................................................................................v

Description of Caution/Warning Symbols ........................................... vii

Caution ............................................................................................ vii

Warning ........................................................................................... vii

Caution or Warning Symbols ........................................................... vii

About This Manual ................................................................................ xiii

Purpose .............................................................................................. xiii

Related Product Literature ................................................................. xiii

Submitting Comments ........................................................................ xiii

CHAPTER 1 Product Overview ............................................................ 1-1

Product Description ........................................................................... 1-1

Applications ....................................................................................... 1-2

How the 3321 Operates .................................................................... 1-3

System History .................................................................................. 1-4

CHAPTER 2 Unpacking and System Setup ........................................ 2-1

Packing List ....................................................................................... 2-1

Mounting the Sensor ......................................................................... 2-2

Ventilation Requirements .............................................................. 2-3

Power Connection ............................................................................. 2-4

Connecting the Computer ................................................................. 2-4

I/O Port .............................................................................................. 2-5

BNC Connectors ............................................................................... 2-5

CHAPTER 3 Description of the APS™ Spectrometer ........................ 3-1

Front Panel ....................................................................................... 3-1

Inlet Nozzle .................................................................................... 3-4

Indicators ....................................................................................... 3-4

Back Panel ........................................................................................ 3-5

AC Power Connector ..................................................................... 3-5

DC Power Input ............................................................................. 3-6

Pump Exhaust ............................................................................... 3-6

Serial Port ...................................................................................... 3-7

I/O Port .......................................................................................... 3-7

BNC Connectors ............................................................................ 3-8

Internal Components ......................................................................... 3-8

CHAPTER 4 APS™ Spectrometer Operation ...................................... 4-1

Sample Setup ................................................................................... 4-1

Collecting Data .................................................................................. 4-4

ix

CHAPTER 5 Theory of Operation ........................................................ 5-1

Sample Flow Path ............................................................................. 5-1

Optics Path ....................................................................................... 5-3

Signal Processing Path ..................................................................... 5-5

APD Module .................................................................................. 5-5

Analog Module ............................................................................... 5-6

Digital Module ................................................................................ 5-7

Particle Coincidence ......................................................................... 5-9

CHAPTER 6 Contacting Customer Service ........................................ 6-1

Technical Contacts ........................................................................... 6-1

Returning the APS Spectrometer for Service ................................... 6-2

APPENDIX A Maintenance ................................................................... A-1

Maintenance Schedule ..................................................................... A-1

Cleaning the Inner Nozzle ................................................................ A-2

Cleaning the Outer Nozzle ................................................................ A-3

Replacing the Filters ......................................................................... A-6

Replacing the EPROM ...................................................................... A-7

Calibrating the APSTM Spectrometer ................................................ A-9

APPENDIX B Troubleshooting ............................................................. B-1

APPENDIX C Using Serial Data Commands ....................................... C-1

Pin Connectors ................................................................................. C-1

Baud Rate ......................................................................................... C-2

Parity (7-Bits Even) ........................................................................... C-2

Stop Bits and Flow Control ............................................................... C-2

Commands........................................................................................ C-3

Set Commands ................................................................................. C-5

Action Commands .......................................................................... C-13

Read Commands (Polled) .............................................................. C-16

Unpolled Commands ...................................................................... C-20

Unpolled Record Formats ............................................................... C-23

How to Input Commands and Troubleshoot the Results ................ C-27

Input Guidelines ........................................................................... C-27

Troubleshooting Input .................................................................. C-28

APPENDIX D Model 3321 Specifications ............................................ D-1

Reader’s Comments

Figures

1 Location of Warning and Information Labels .................................... vi

1-1 Model 3321 Aerodynamic Particle Sizer® Spectrometer ................. 1-2

1-2 Double-Crested Signal From Particles Passing Through

Overlapping Beams ......................................................................... 1-3

2-1 Remove the Rubber Feet on the Base Plate to Mount the

Model 3321 on Another Surface ..................................................... 2-2

2-2 Install the Sensor on a Clean, Hard Surface and Provide

Adequate Clearance for Ventilation ................................................ 2-3

x Model 3321 Aerodynamic Particle Sizer® Spectrometer

Tables

2-3 Serial Port Connector on the Back of the Model 3321 .................... 2-4

2-4 I/O Port of the Model 3321 APS™ Spectrometer ........................... 2-5

3-1 Front Panel of the Model 3321 APS™ Spectrometer ..................... 3-2

3-2 Model 3321 Menu Layout ................................................................ 3-3

3-3 Back Panel of the Model 3321 APS™ Spectrometer ...................... 3-5

3-4 24V DC Power Input Pin Designations ........................................... 3-6

3-5 I/O Port Pin Designations ................................................................ 3-7

3-6 Internal Diagram of the Model 3321 APS™ Spectrometer ............. 3-9

4-1 APS™ Spectrometer Menu ............................................................. 4-2

5-1 Aerosol Flow Through the Model 3321 APS™ Spectrometer ......... 5-2

5-2 APS™ Spectrometer Optics Cross Section .................................... 5-4

5-3 Typical Example of a Double Crested Signal .................................. 5-5

A-1 Location of EPROM Chips on APS™ Spectrometer Digital

PC-Board ........................................................................................ A-8

C-1 SERIAL PORT Pin Designations ................................................... C-1

C-2 Serial Command Tables ................................................................. C-4

3-1 Power Connections for 24V DC Power Input .................................. 3-6

3-2 Signal Levels for I/O Port Configurations ........................................ 3-7

4-1 Description of Menu Items ............................................................... 4-3

A-1 Maintenance Schedule ................................................................... A-1

B-1 Troubleshooting Symptoms and Recommendations ..................... B-1

C-1 Signal Connections for RS-232 Configurations .............................. C-2

C-2 Digital Output Pin Settings ............................................................. C-8

C-3 Analog Voltage Output Settings ................................................... C-10

C-4 Troubleshooting Serial Commands .............................................. C-28

D-1 Specifications of the Model 3321 Aerodyamic Particle Sizer®

(APS™) Spectrometer .................................................................... D-1

Contents xi

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xii Model 3321 Aerodynamic Particle Sizer® Spectrometer

About This Manual

Purpose

This is an operation and service manual for the Model 3321 Aerodynamic
Particle Sizer (APSTM) Spectrometer.

Related Product Lite r ature

 Aerosol Instrument Manager

(part number 1930064 TSI Incorporated)

 Model 3302A Diluter Manual (part number 1933786 TSI Incorporated)
 Model 3433 Small Scale Powder Disperser Manual (part number

1933769 TSI Incorporated)

 Model 3306 Impactor Inlet Manual (part number 1933787 TSI

Incorporated)

Submitting Com m ents

TSI values your comments and suggestions on this manual. Please use
the comment sheet, on the last page of this manual, to send us your

opinion on the manual’s usability, to suggest specific improvements, or to

report any technical errors.

If the comment sheet has already been used, send your comments to:

TSI Incorporated
500 Cardigan Road
Shoreview, MN 55126
Fax: [phone]
E-mail Address: [e-mail]

®

Software for APS™ Sensors Manual

xiii

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xiv Model 3321 Aerodynamic Particle Sizer® Spectrometer

C H A P T E R 1

Product Overview

This chapter contains a product description of the Model 3321
Aerodynamic Particle Sizer® (APS™) spectrometer and a brief description
of how the instrument operates.

Product Description

The Model 3321 APS™ spectrometer, shown in Figure 1-1, is a high­performance, general-purpose particle spectrometer that measures both
aerodynamic diameter and light-scattering intensity. The Model 3321
provides accurate count size distributions for particles with aerodynamic
diameters from 0.5 to 20 micrometers (m). It detects light-scattering
intensity for particles from 0.3 to 20 m.

For setup and initial sampling, the Model 3321 can be operated without a
computer. To save, interpret, or print data, however, it must be connected
to a computer or some other data collection system. The Aerosol
Instrument Manager® software with Model 3321 Module is included with the
sensor to provide computer controlled operation and data interpretation.

The Model 3321 includes an LCD display and control knob. The control
knob is a rotary, push-button encoder that gives you an easy way to scan
through data on the LCD Display as well as to display and change settings.

Using the control knob you can select functions and read operating
parameters from a menu displayed on the screen. Functions include start,
stop, and length of measurement; parameters include inlet pressure, flow
rate, and temperature. During the sampling process, the size distribution is
shown on-screen in real time. You can also use the control knob to focus
on a specific channel of the sensor and obtain detailed information about
the concentration, particle size, and total particle count

Five LEDs on the front panel provide a visual indication of the status of
important sensor functions.

1-1

Applications

Figure 1-1

Model 3321 Aerodynamic Particle Sizer® Spectrometer

The Model 3321 APS™ spectrometer has application in the following
areas:

 Inhalation toxicology
 Atmospheric studies
 Ambient air monitoring
 Drug-delivery studies
 Powder sizing
 Filter and air-cleaner testing
 Indoor air-quality monitoring
 Biohazard detection
 Basic research
 Characterization of test aerosols used in particle-instrument calibration
 Performance evaluations of other aerodynamic devices
 Pesticide/herbicide-droplet calibration tests

1-2 Model 3321 Aerodynamic Particle Sizer Spectrometer

How the 3321 Operates

Light Scatter
to Electrical
Pulse

Aerodynamic diameter is the most important size parameter because it
determines a particle’s airborne behavior. The Model 3321 is specifically
engineered to perform aerodynamic size measurements in real time using
low particle accelerations.

Time-of-flight particle sizing technology involves measuring the
acceleration of aerosol particles in response to the accelerated flow of the
sample aerosol through a nozzle. The aerodynamic size of a particle
determines its rate of acceleration, with larger particles accelerating more
slowly due to increased inertia. As particles exit the nozzle, the time of
flight between the Model 3321s two laser beams is recorded and converted
to aerodynamic diameter using a calibration curve.

Previous time-of-flight spectrometers used two tightly focused laser beams,
resulting in two distinct signals for each particle.

As shown in Figure 1-2, the Model 3321 overlaps the two laser beams,
producing one double-crested beam profile. Each particle creates a single,
continuous signal that has two crests. Particles with only one crest
(phantom particles) or more than two crests (coincidence error) are not
used in building size distribution calculations (they are logged for user­defined post analysis concentration correction). The result is an extremely
accurate count distribution with almost no background noise to distort mass
distribution calculations.

Figure 1-2

Double-Crested Signal From Particles Passing Through Overlapping Beams

The Model 3321 also provides a light-scattering measurement by
examining each particle’s side-scatter signal intensity. This measurement
produces a second distribution that can be plotted against aerodynamic
size to gain additional information about the aerosol sample.

Refer to Chapter 5, “Theory of Operation,” for a detailed description.

Product Overview 1-3

System History

The first APS™ spectrometer manufactured by TSI was designated the
Model 3300. It consisted of a sensor with a parallel interface to an Apple II+
computer. This sensor was the first self-contained real-time instrument to
give aerodynamic particle size in the 0.5 to 15 µm range. The sensor was
based on work done by Agarwal and Fingerson (1979), and was in
production from 1982 to 1987.

In 1987 the Model 3310 APS™ spectrometer was released. It used a serial
interface to an IBM PC. This sensor had timer improvements allowing it to
detect particles from 0.5 to 30 µm.

In 1993, the Model 3310 APS™ spectrometer received a face-lift and some
minor engineering changes. This brought the instrument up-to-date in
terms of electrical compliance and replaced obsolete parts. A new color
scheme brought the APS™ spectrometer into line with the family of TSI
scientific particle instruments.

The Model 3320 APS™ spectrometer is a complete redesign of earlier
APS™ spectrometer models and began shipping in early 1997. This
smaller, ruggedized sensor includes improvements such as: a front panel
display, solid-state laser and avalanche photodetector, automatic flow
control, barometric pressure compensation, and error reducing signal
processing. Collecting and analyzing data from the Model 3320 is possible
with the Windows
Aerosol Instrument Manager® software.

The Model 3321 has several slight design and significant performance
improvements over the 3320 for qualitative mass weighted distributions.
The sample eduction nozzle has been redesigned to more effectively
transport particles out of the detection region to the exhaust. This
effectively eliminates recirculating particles under most operating
conditions giving much better mass calculated distributions. The Model
3321 also has improved signal and data processing allowing more
aerodynamic size resolution in correlated mode with only slightly less pulse
height resolution than the Model 3320.

®

XP or Vista® (32-bit only), or Windows 7 (32 or 64-bit),

1-4 Model 3321 Aerodynamic Particle Sizer Spectrometer

Packing List

Qty

Description

Part No.

1

Model 3321 Sensor

332100

1

Model 3321 Aerodynamic Particle Sizer

®

Spectrometer

User’s Manual

1930092
1

Aerosol Instrument Manager® Software

390059

1

Line Cord

1303053 or
1303075

1

Serial Cable (9 pin, M–F, 4 meter)

962002

1

USB-to-Serial Converter

1102138

24 in.

Tubing 5/16  3/16

3001248

1

Fitting, Pump Exhaust Adapter

1601836

C H A P T E R 2

Unpacking and System
Setup

This chapter provides information concerning the accessories shipped with
the sensor and describes basic setup procedures.

Table 2-1 provides a packing list of all items that should have been shipped
to you as the APS™ spectrometer and accessory kit. Please compare the
list to the items you received. If any items are missing, notify TSI
immediately.

Table 2-1

Accessories Packing List

2-1

Mounting the S e nsor

3.28

8.80

.64

2.08

10.30

2.08

[52.8 mm]

[262 mm]

[52.8 mm]

[16.3 mm]

[223.5 mm]

[83.3 mm]

The Model 3321 APS™ spectrometer requires no special mounting
requirements other than the ventilation requirements (see below). The
cabinet has four non-marking rubber feet that give the instrument a good
grip on clean, level surfaces. The rubber feet (Figure 2-1) are installed in
the cabinet using integrated 8-32 UNC threaded fasteners and can be
removed (by unscrewing) to allow other mounting fasteners to be used.

Note: If the cabinet is mounted to a plate, drill holes in the plate to match

the ventilation holes in the bottom of the cabinet or use standoffs to
raise the bottom of the cabinet at least ½ inch (1.2 cm) above the
mounting plate.

2-2 Model 3321 Aerodynamic Particle Sizer Spectrometer

Figure 2-1

Remove the Rubber Feet on the Base Plate to Mount the Model 3321 on
Another Surface

2.00
[50.8 mm]

2.00
[50.8 mm]

2.00
[50.8 mm]

Ventilation Requirements

The APS™ Sensor cabinet is designed to be cooled by room air drawn in
from the sides and bottom of the cabinet and exhausted through the back
of the cabinet.

As shown in Figure 2-2, the cabinet should be installed with at least 2-inch
(50 mm) clearance between the back panel and any other surface. The
sides should have at least 2-inch (50 mm) clearance between the cabinet
and any other surface. Most important, the cabinet should be set on a
clean, hard surface so that the exhaust air can move freely from the
cabinet.

Figure 2-2

Install the Sensor on a Clean, Hard Surface and Provide Adequate Clearance
for Ventilation

Unpacking and System Setup 2-3

Power Connection

Connect the AC power cord (supplied) to the AC POWER IN connection on
the back of the Model 3321 and then into an available power outlet. It is not
necessary to select the correct voltage, the sensor accepts line voltage of
85 to 260 VAC, 50 to 60 Hz, 100 W max., single phase. The connection is
self regulating.

Toggle the on/off switch at the POWER connection to the on position to
verify the sensor has power.

Alternately, connect 24 VDC to the DC POWER IN connection. Contact
TSI to order the necessary connector.

Connecting the Compute r

Connect the serial port of an IBM-compatible computer to the SERIAL
PORT connector on the back of the Model 3321 (Figure 2-3). Use the
4-meter cable provided. If you need a longer cable, use a standard IBM
9-pin, serial extension cable.

Figure 2-3

Serial Port Connector on the Back of the Model 3321 APS™ Spectrometer

2-4 Model 3321 Aerodynamic Particle Sizer Spectrometer

I/O Port

The APS™ spectrometer has a 15-pin, D-subminiature connector port
(Figure 2-4) labeled I/O PORT. This port provides three digital input and
three digital output pins that can be used to control associated equipment
or set device using commands described in Appendix C. This port also has
two analog input pins to allow data logging of analog voltages from external
devices such as temperature or relative humidity sensors.

Figure 2-4
I/O Port of the Model 3321 APS™ Spectrometer

BNC Connectors

There are three BNC connectors on the Model 3321 for output of the
following signals. Refer to Chapter 3 for a detailed description of each of
the BNC connectors.

 Analog Out
 Time-of-Flight
 Pulse Out

Unpacking and System Setup 2-5

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2-6 Model 3321 Aerodynamic Particle Sizer Spectrometer

C H A P T E R 3

Description of the
APS™ Spectrometer

This chapter describes the front panel, back panel and internal
components of the Model 3321 Aerodynamic Particle Sizer® (APS™)
Spectrometer.

The front panel features LEDs to provide basic on/off status for five
instrument functions and an LCD display and control knob that work
together to provide continuous real-time sampling information and access
to a menu of system functions. Through this menu you can perform initial
sample setup and view detailed instrument status.

The back panel provides power and communications connections as well
as sample exhaust outlet.

Internal components consist of the flow system, the optics system, and the
signal processing electronics.

Front Panel

The main components of the front panel are the LCD display, the control
knob, and the five status LEDs as shown in Figure 3-1.

The LCD display is used as a local interface to the APS™ sensor. Although
most users will want to use a computer connected to the APS™
spectrometer to display, collect and save data, the LCD display allows the
user to change settings and display data in various formats at the sensor
itself.

3-1

LCD Display

Inlet Nozzle

Control
Knob

Status LEDs

Figure 3-1

Front Panel of the Model 3321 APS™ Spectrometer

The 320  240 pixel LCD display provides continuous real-time display of
sample data.

Sample data includes:

 Size distribution.
 Concentration.
 Mean aerodynamic particle size.
 Total particle count.

There are several operations you can perform using the control knob with
the display.

3-2 Model 3321 Aerodynamic Particle Sizer Spectrometer

To turn the display on

Press or rotate the control knob.

To view information about a specific
channel displayed on the graph

Turn the control knob so that the cursor is positioned on the bar of the
appropriate channel. The channel size and concentration are displayed at
the bottom of the screen. The scale automatically changes to
accommodate the sample range and mode.

To clear the accumulator

Turn the control knob all the way to the right of the display. This will cause
three buttons to appear at the bottom of the screen. Continue turning until
the Clear button is highlighted, then press the control knob.

To start or restart a sample

Turn the control knob all the way to the right of the display. This will cause
three buttons to appear at the bottom of the screen. Continue turning until
the Start button is highlighted, then press the control knob.

To change from the graphic display to the
system Menu

Turn the control knob all the way to the right of the display. This will cause
three buttons to appear at the bottom of the screen. Continue turning until
the Menu button is highlighted, then press the control knob. The Menu is
shown in Figure 3-2, and allows you to select various sampling
parameters and view many system parameters. Refer to Chapter 4 for a
description of how to make selections and change values on the Menu.

Figure 3-2

Model 3321 Menu Layout

Fine adjustment of the control knob (i.e., moving from one channel to the
next) is best accomplished using the outer edge of the knob. Faster
movement (i.e., scrolling across the screen to reach the menu) is best
accomplished using your index finger and the dimple in the knob.

Description of the APSTM Spectrometer 3-3

Inlet Nozzle

The inlet nozzle on the top of the Model 3321 is designed so that aerosol
can be sampled from a chamber or open air with good efficiency. Tubing
can be attached to the inlet to sample when necessary. The inlet is
.746 inches (18.9 mm) in diameter for use with ¾-inch Swagelok®-type
connectors or with slightly smaller inner diameter flexible tubing.

Note: Conductive tubing is recommended for use with the APS™

spectrometer to minimize particle loss due to electrostatic charge.
Suitable tubing is available from TSI.

Indicators

There are five status LEDs on the APS™ spectrometer: PARTICLE, HI
CONC, FLOW, LASER, and POWER.

 The amber PARTICLE LED blinks once each time a particle passes

through the sensor. In normal room air, the LED will appear to be lit
constantly. When sampling aerosols in low concentrations, the LED will
appear to flicker.

 The amber HI CONC LED indicates that the concentration of particles

being sampled is above the recommended level to prevent coincidence
(see Chapter 5, “Theory of Operation”). When this LED is lit, many of
the particles are ignored in the counting process since they cannot be
accurately sized. The default setting is 1000 particles/cm3.

 The green FLOW LED indicates that both the sample and sheath

airflows are within their specified range.

 The green LASER LED indicates that the laser is on and functioning

properly. A flashing LED may mean that the laser is not able to operate
at the set power. See SL command.

 The green POWER LED indicates that power is supplied to the

instrument.

®

Swagelok is a registered trademark of Swagelok® Companies, Solon, Ohio.

3-4 Model 3321 Aerodynamic Particle Sizer Spectrometer

Back Panel

AC Power in
(w/ switch)

DC Power in
Pump Exhaust

Cooling Fan

Serial Port
Analog Out

Time Of Flight

Pulse Out

I/O Port

As shown in Figure 3-3, the back panel of the APS™ spectrometer
Model 3321 allows for power and data connections. The back panel also
has a pump exhaust port and a fan. The cooling fan has a finger guard to
prevent fingers, pens, etc., from being poked into the fan.

Figure 3-3
Back Panel of the Model 3321 APS™ Spectrometer

AC Power Connector

The AC Power Connector accepts the line cord (supplied) to provide AC
power to the sensor. The connector has a built-in on/off switch. Power
consumption and line voltage specifications can be found in Appendix D.

Note: Make certain the line cord is plugged into a grounded power outlet.

Position the Model 3321 so the power cord connector is easily
accessible.

Description of the APSTM Spectrometer 3-5

DC Power Input

1

2

4

3

The DC power connector is a quarter-turn quick-connect entry point that
allows you to power the APS™ spectrometer with a 22 to 26 VDC (24 VDC
nominal) 4A max. power source. This power could be supplied by aircraft
power or two 12 VDC automotive batteries in series. Contact TSI for the
adapter cable (TSI P/N 1035551), and instructions on using this power
method.

Figure 3-4

24V DC Power Input Pin Designations

Table 3-1

Power Connections for 24V DC Power Input

Pin Number Signal

1 GND Chassis GRN/YEL
2 +24V Blue
3 GND Brown Shield
4 Chassis Shield

Pump Exhaust

Sample aerosol is exhausted through the Exhaust Port.
The pump exhaust connector is a ¼-inch Swagelok-style connector that

allows control of the exhaust flow. The exhaust can be vented to a hood or
connected in line to equalize pressure when sampling from a chamber or in
an aircraft. The exhaust flow is 5 to 6 L/min. Make certain the exhaust tube
allows the exhausted sample to flow freely (check for crimps and
constrictions).

If the aerosol sample is exhausted without tubing, make certain you do not
block the Pump Exhaust.

3-6 Model 3321 Aerodynamic Particle Sizer Spectrometer

8765432

1

15 14 13 12 11 10 9

Serial Port

The Serial Port is a standard RS-232 serial connection that allows
communications between the system computer and the Model 3321 APS™
spectrometer. Serial commands are sent to and from the computer to
provide instrument status and collect data information.

If you are developing specialized software for the APS™ spectrometer or
performing troubleshooting, refer to Appendix C, "Using Serial Data

Commands,". This appendix provides a complete description of the Serial

Data Commands, as well as signal connections.

I/O Port

This 15-pin, D-subminiature connector port provides three digital input and
three digital output pins. It allows various signals to be sent to a data logger
or control switches. Refer to Appendix C, "Using Serial Data Commands,"
for serial commands to control the I/O Port. This port also has two analog
input pins to allow data logging of analog voltages for external devices
such as temperature sensors or relative humidity sensor.

Figure 3-5

I/O Port Pin Designations

Table 3-2
Signal Levels for I/O Port Configurations

Pin Number I/O Signal Levels

1 Digital Input 1 0, 5V
2 Digital Input 2 0, 5V
3 Digital Input 3 0, 5V
4, 5 Digital GND Ground
6 +5V Digital Supply Out 5V
7 Analog Input 1 0 to 10V
8 Analog Input 2 0 to 10V
9, 10 Digital GND Ground
11 Digital Output 1 0, 5V
12 Digital Output 2 0, 5V
13 Digital Output 3 0, 5V
14 Digital GND Ground
15 Analog GND Ground

Description of the APSTM Spectrometer 3-7

BNC Connectors

 Digital PC board
 Analog PC board
 Sheath flow pump
 Total flow pump
 Filters

 Power Supply
 Optics
 Detector PC board
 Laser PC board
 Power PC board

Three BNC connectors provide the following signals.

Analog Out

The Analog Out BNC connector provides a programmable analog signal
that can be sent to a strip chart recorder or other analog device. Refer to

Appendix C, "Using Serial Data Commands," for serial commands that

control the signal output.

Time of Flight

The Time of Flight BNC connector provides a digital signal corresponding
to the gated level of the raw analog time of flight signal for each particle.

Pulse Out

The Pulse Out BNC connector provides amplified raw signals from the
photodetector. This signal can be used with an oscilloscope, for example,
to examine secondary characteristics of the pulses.

Internal Components

The location of the functional systems and electronics of the Model 3321
APS™ spectrometer are shown in Figure 3-6 and include:

The only serviceable components of the Model 3321 APS™ spectrometer
are the filters, which require routine maintenance (refer to Appendix A). For

a general description of these components, refer to Chapter 3, “Description

of the APSTM Spectrometer.” For a more detailed description, refer to

Chapter 5, “Theory of Operation.”

3-8 Model 3321 Aerodynamic Particle Sizer Spectrometer

Analog
PC-Board

Digital
PC-Board

Sheath Flow
Pump

Filters

Detector
PC-Board

Power
Supply

Optics

Power
PC-Board

Total Flow
Pump

Laser
PC-Board

Figure 3-6

Internal Diagram of the Model 3321 APS™ Spectrometer

Description of the APSTM Spectrometer 3-9

(This page intentionally left blank)

3-10 Model 3321 Aerodynamic Particle Sizer Spectrometer

C H A P T E R 4

APS™ Spectrometer
Operation

This chapter describes how to set up and operate the Model 3321 at the
sensor using the control knob and LCD display. You can perform the same
operations from your computer using the Aerosol Instrument Manager®
software with Model 3321 module.

In most cases you will want to set up initial sampling parameters at the
sensor and then, once you have verified that sampling conditions are as
desired, use the computer to collect, store, interpret, and print the sample
data. (Refer to the Aerosol Instrument Manager® Software for APS™
Sensors Manual (P/N 1930064) for more information on operating the
software.)

Although you can set up parameters and begin sampling at the APS™
sensor, the data shown on the LCD display is not stored, nor can it be sent
to a printer. To save or print data, you must collect it using the computer
interface and the Aerosol Instrument Manager® software.

The data displayed on the front panel may not exactly match data recorded
with the Aerosol Instrument Manager® software due to rounding
differences. Also, concentration displayed for <0.523 µm on the front panel
includes event 1 data and may not match the concentration reported by the
Aerosol Instrument Manager® software. When performing any critical or
detailed data analysis, Aerosol Instrument Manager® software should be
used. The front panel LCD display should only be used as a remote
indicator of instrument and measurement status.

Sample Setup

These instructions assume that the APS™ spectrometer is connected to an
appropriate power source and the power on/off switch on the back panel is
switched to the on position.

1. Turn the control knob clockwise until the cursor runs off the right side
of the display and the CLEAR, START, and MENU buttons appear.
Continue turning the control knob until Menu button is highlighted; then
press the control knob. The menu shown in Figure 4-1 appears.

2. Turn the control knob clockwise until the cursor falls on the Sample
Time[s] command. Press the control knob once. Turn the control knob

4-1

clockwise or counterclockwise until the sample time is set as desired.
Then press the control knob to lock in that time.

3. Turn the control knob to select other commands or verify other
settings. All of the items on the menu are described in Table 4-1. When
you are finished using the menu, turn the control knob until the cursor
stops on the Exit command at the top or bottom of the menu and press
the control knob to return to the graphical display.

4. After you exit the Menu, turn the control knob to highlight the START
button and press the control knob. The APS™ spectrometer will
immediately begin sampling according to the parameters set on the
menu.

Figure 4-1
APS™ Spectrometer Menu

5. Monitor the display to verify that sampling is progressing as you
intended. You can monitor the display until the sample period ends or
go to the computer to begin a sample from there.

To inspect the sample data that has been collected for a specific
channel, turn the control knob until the cursor falls on the channel you

want to inspect. The channel’s particle diameter and concentration in

particles per centimeter3 are displayed below the graph. Inspect other
channels in the same manner.

6. Return to the Menu to modify the sample time or set other parameters
as necessary until you are satisfied that sampling is set up as desired.

4-2 Model 3321 Aerodynamic Particle Sizer Spectrometer

Command

Function (see also Appendix C for serial commands

related to Menu Items).

Exit

Exit the Menu and display graphical information.

Sample Time [s]

Set the total sample time. Can be set from 1 to 64,800
seconds (18 hours) in summed mode and from 1 to 300
seconds in average mode. Default is 20 seconds.

Sample Mode

Select Summed|Averaged|Sum.Corr. Summed
displays the total number of particles sampled for each
channel. Averaged displays a calculated average
number of particles sampled for each channel. Sum.

Corr will not show useable data at the sensor’s LCD

display. Use the APS™ spectrometer software to
interpret. The default is Summed.

Sample Type

Continuous|Single. Continuous sampling begins a new
sample immediately following the end of the previous
sample. Single sample takes one sample for the set
sample time and then stops.

Pumps

Turn pumps on and off. Default is on.

Sound

Turn on and off the beeping sound that is activated when
the Hi-Conc. limit is exceeded. The default is on. If
necessary, set (reset) the limit from the computer software
setup program as described in Chapter 5 or using a serial
data command as described in Appendix C.

Baud Rate

Select the baud rate at which the sensor will
communicate with your computer. Use the control knob
to select: 38400, 19200, or 9600. The default is 9600.

Note: 38,400 must be used in correlated mode.

Inlet Pressure
[mbar]

Displays the current inlet pressure of the sample. This
value should correspond to your atmospheric pressure.
No default value.

Sheath Flowrate
[lpm]

Displays the flow rate of the outer nozzle (sheath)
aerosol. This reading will approximate 4.0 liters (±0.1)
per minute. No default value.

Aerosol Flowrate
[lpm]

Displays the flow rate of the inner nozzle (sample)
aerosol. This reading will approximate 1.0 (±0.1) liter per
minute. No default value.

Total Flowrate [lpm]

Displays the total flow rate of the sample aerosol. This
reading will approximate 5 (±0.2) liters per minute
(unless sheath or sample flow has been modified). Used
to verify proper sensor operation. No default value.

Optics
Temperature [C]

Displays the temperature of the optics components.
Used to verify proper sensor operation. No default value.

Note: This is also the APD detector temperature.

Cabinet
Temperature [C]

Displays the temperature inside the APS™
spectrometer. No default value.

Laser Current [mA]

Displays the laser current in milliamps. Range should be
between 0 and 100 mA. This value rises as the laser
ages. Used for diagnostic purposes.

Table 4-1
Description of Menu Items

APSTM Spectrometer Operations 4-3

Command

Function (see also Appendix C for serial commands

related to Menu Items).

Laser Power [%]

Displays the percent of laser power used from 0 to
100%. Default is 75%. This value is field selectable but
should not be changed except for diagnostic purposes.
Changing this setting will alter the calibration. Refer to

Chapter 5 or Appendix C.

Laser

Turn the laser on and off. Default is on. Generally, the

laser is on whenever the instrument is running. You

might want to turn it off for diagnostic purposes.

APD Voltage [V]

Displays the voltage of the Avalanche Photodetector

(APD). Changing the APD voltage with this setting

disables APD autocalibration (see below).

APD Max Vop [V]

When the APS™ spectrometer is powered up, the APD

voltage is set to APD Max Vop based on the temperature

of the APD. This temperature compensated setting

should give the APS™ spectrometer the maximum

sensitivity to small particles.

APD

Autocalibration

Enables the APD temperature compensation algorithm

when set to On. When set to Off, the APD voltage will not

change with APD temperature. This setting will always be

enabled when the instrument is first powered on.

Alarm Level

[pt/cm3]

Level of total particle concentration at which the APS™

spectrometer will issue a high concentration alarm. The

HI CONC led on the front panel will be turned on and the

high concentration flag (see RF command) will be set;

and if the sound is turned on, the APS™ spectrometer

will beep. Default is 1000.

End of Sample

Pause

When enabled, this setting freezes the display for 4

seconds at the end of a sample when in continuous

sample mode. This gives you a chance to view the

sample or to select Pause from the main menu. Default

is off.

Display Image

Set the image Positive/Negative for the LCD display.

Positive is black letters on light background. Negative is

white letters on dark background.

Firmware Version

Displays the version number of the firmware installed in

the APS™ spectrometer.

Exit

Exit the Menu and display graphical information.

Collecting Data

After the Model 3321 APS™ spectrometer is set up and operating as
desired, use the computer and Aerosol Instrument Manager software to
collect, save, interpret, and print sample data. Refer to the Aerosol
Instrument Manager® Software for APS™ Sensors Manual (P/N 1930064)
for more information on operating the software.

4-4 Model 3321 Aerodynamic Particle Sizer Spectrometer

C H A P T E R 5

Theory of Operation

The Model 3321 is a time-of-flight spectrometer that measures the velocity
of particles in an accelerating airflow through a nozzle.

In the instrument, particles are confined to the centerline of an accelerating
flow by sheath air. They then pass through two broadly focused laser
beams, scattering light as they do so. Side-scattered light is collected by an
elliptical mirror that focuses the collected light onto a solid-state
photodetector, which converts the light pulses to electrical pulses. By
electronically timing between the peaks of the pulses, the velocity can be
calculated for each individual particle.

Velocity information is stored in 1024 time-of-flight bins. Using a
polystyrene latex (PSL) sphere calibration, which is stored in non-volatile
memory, the Model 3321 APS™ spectrometer converts each time-of-flight
measurement to an aerodynamic particle diameter. For convenience, this
particle size is binned into 52 channels (on a logarithmic scale).

The particle range spanned by the APS™ spectrometer is from 0.5 to
20 µm in both aerodynamic size and light-scattering signal. Particles are
also detected in the 0.3 to 0.5 µm range using light-scattering alone, and
are binned together in one channel.

The APS™ spectrometer is also capable of storing correlated light­scattering-signal data and time-of-flight data.

Sample Flow Path

The sample flow path in the Model 3321 APS™ spectrometer is illustrated
in Figure 5-1. Aerosol is drawn into the inlet and is immediately split into a
sample flow, through the inner nozzle, and a sheath flow, through the outer
nozzle.

The sheath flow is filtered and controlled by the sheath flow pump. The
sheath flow is controlled by measuring the pressure drop through a sharp­edged sapphire orifice. This pressure drop is converted by the firmware to
a volumetric flow with compensation for absolute atmospheric pressure.

5-1

Elliptical

Mirror

Beam

Dump

Inner Nozzle/Sample Flow

(1 L

/min)

Accelerating

Orifice Nozzle

T

otal Flow

(5 L

/min)

Aerosol In

Outer Nozzle/Sheath Flow

(4 L

/min)

Filter

Filter

Filter

Filter

Sheath-Flow

Pump

Total-Flow

Pump

Absolute

Pressure

Transducer

Orifice

Sheath-Flow

Pressure

Transducer

Total-Flow

Pressure

Transducer

Collimated

Diode

Laser

Detection

Area

Beam-Shaping Optics

Figure 5-1

Aerosol Flow Through the Model 3321 APS™ Spectrometer

After passing through the orifice, the sheath flow is reunited with the
sample flow at the accelerating orifice nozzle. This flow confines the
sample particles to the center stream and accelerates the airflow around
the particles. In this way, small particles (which can accelerate with the
flow) reach a higher velocity than larger particles (which, due to inertia, lag
behind the flow of the air stream).

Particle velocity is then measured in the optics chamber (refer to “Optics

Path and Signal Processing Path,” below).

After measurement, the particle stream exits the optics chamber, drawn by
the total flow pump. The combined flow is controlled by the total flow pump
and the pressure drop across the accelerating orifice nozzle.

Sample flow is filtered before and after each of the two pumps. The filter
upstream of the pump protects the pump from contamination. The filter
downstream of the pump prevents contamination of the flow as the pump
vanes wear.

5-2 Model 3321 Aerodynamic Particle Sizer Spectrometer

Optics Path

The first component in the optics path, see Figure 5-2, is the laser diode.
Light coming from the laser is polarized vertically. Using a polarization
rotator (polymer half-wave plate) the polarization of the laser is rotated by
45 degrees. After rotation, the beam passes through negative and positive
spherical lenses to focus the beam under the particle stream. A
polarization beam splitter is then used to split the vertical and horizontal
components of the beam into two separate beams spaced by 90 to
100 µm. The top beam (closest to the nozzle) is polarized horizontal and
the bottom beam is polarized vertical. Spacing is controlled by the
thickness of the splitter.

The beam pair next passes through a negative cylindrical lens. This lens
controls the width of the beams independent of the focus under the particle
stream. Two vertical knife edges clip the noisy edges of the beams to give
a clean beam under the particle stream. A window is used solely as a
sealing surface to keep the optics chamber separate from the optical
elements, and a final aperture is used to stop stray light from the far edges
of the beams before the beams reach their focal point under the particle
stream.

The beams are then passed through a large aperture into a dual
polarization beam stop. The first beam stop uses neutral density filter glass
placed at the Brewster angle for vertical polarization. This captures all of
the vertical polarization and most of the horizontal polarization. The
remaining portion of the horizontal polarization is reflected into a second
Brewster angle where it is captured. The large aperture in front of the beam
stops prevents light from the beam stops escaping and helps to keep the
beam stop glass clean.

The inset of Figure 5-2 shows that light scattered by the particle stream is
collected by an elliptical mirror and focused onto a solid-state avalanche
photodiode (APD) detector. The detector then converts the light pulses into
electrical pulses.

Theory of Operation 5-3

Knife Edge

Neg Cyl Lens

Calcite
Plate

Pos Spherical
Lens

Neg Spherical
Lens

Laser
Steering

Laser
PCB

Laser
Diode

Polarization

Rotator

Window

Aperture
Plate

Aperture
Plate

Beam Stop

1st Polarization

Beam Stop

2nd Polarization

Elliptical
Mirror

Detector

Detector

PCB

Figure 5-2

APS™ Spectrometer Optics Cross Section

5-4 Model 3321 Aerodynamic Particle Sizer Spectrometer

Signal Processing Path

Signal processing is performed in the APD, Analog, and Digital modules.

APD Module

Signal processing begins at the APD module, where scattered light from
the particle is detected and converted into an analog voltage signal. This
signal, referred to as a double crested signal, consists of a pair of peaks.

Figure 5-3

Typical Example of a Double Crested Signal

Each peak represents the presence of the particle in the center of the
individual laser beams and can range in amplitude 0–10 volts. The signal is
gained and buffered into two channels. One channel is for very small
particles and has a high gain. The other channel is for large particles and
has a low gain. Once the signals are gained up they are passed to the
analog module.

Theory of Operation 5-5

Analog Module

Signals arriving at the analog module are sent to three different circuits for
processing: the gate and differential circuits, and the side-scatter-intensity
circuit. The output of these three circuits are then passed on to the digital
module.

Gate Circuit

The gate circuit produces a digital gate (GATE) signal, or gate window,
which represents the presence of the particle in the measurement volume.
Producing this signal is accomplished by first adding the high gain and 10
times the low gain signal together. This addresses the dynamic range of
pulse heights, roughly three orders of magnitude, for the size range of
particles (0.3 to 20 m).

This summed signal is then sent through a delay line. Two different taps
from this delay line, roughly 300 ns apart, are added together, filtered,
gained, and clamped. This creates a signal that has very little valley in it
and prevents it from going below the gate threshold. This signal is
compared to the gate threshold, typically about 100 mV and can be set by
the user through a serial command (see Appendix C). If it is above the
threshold, the digital gate (GATE) signal goes active. When the signal
drops back below the threshold, the GATE signal goes inactive. The time
during which the GATE signal is active is called the gate window.

Differential Circuit

The differential circuit produces a digital difference (DIFF) signal that
indicates the zero crossings of the differentiated double crested analog
signal, which occur when the slope of the signal is equal to zero. Zero
crossings, DIFF signal transitions, are positive going for a valley and
negative going for a peak. The time between the negative going zero
crossings of the differential signal (the peaks of the double crested analog
signal) is called the transit time, or time-of- flight (TOF), of the particle. This
time ranges from about 800 ns to 4.1 µs. It is this time, along with the
calibration of the instrument, that determines the aerodynamic size of the
particle.

The differential circuit produces the differential signal by taking two
different taps from the delay line used in the gate circuit, roughly 300 ns
apart and delayed from the first tap of the gate circuit by 20 ns. These two
signals are then subtracted from each other, filtered, gained, clamped, and
then filtered again. This produces a analog difference signal, both positive
and negative, that is analogous to a differential signal. This difference
signal is compared against a difference threshold, typically 0 V and is set
via a potentiometer adjustment at the factory, producing a digital difference
(DIFF) signal. If the difference signal is at or below the threshold, the DIFF
signal is inactive. When the difference signal goes above the threshold the
DIFF signal will go active giving a rising edge. When the summed signal
goes through a peak the difference signal falls below the threshold and the
DIFF signal will go inactive giving a falling edge. The DIFF signal will give a
rising edge when going through the valley, and then give a falling edge

5-6 Model 3321 Aerodynamic Particle Sizer Spectrometer

Detection
Threshold

when going through the second peak. It will stay inactive when the signal
falls back to or below the difference threshold.

Side-Scatter Circuit

The third circuit is the side-scatter-intensity circuit. Both double crested
analog signals from the low gain and the high gain outputs of the APD
module are filtered, gained, clamped, and input to separate peak hold
circuits, which hold the pulse height of the highest peak of each signal. An
A/D converter is then used to give the digital value of each of the side­scatter-intensity pulse heights.

The high gain value is checked for an over range in the A/D digital value,
which indicates a large particle. If it is over range, the digital value from the
low gain A/D is output to the digital module. If it is not over range, the
digital value from the high gain A/D is output.

After the particle is processed, the peak hold circuits are cleared and
readied for the next particle.

The GATE signal, DIFF signal and the side-scatter circuit output are then
presented to the digital module to be processed and recorded.

Digital Module

The GATE and DIFF digital signals from the analog module are used to
trigger a high speed timer which has 4.0 ns resolution and a maximum
range of 4.096 s. After the gate signal goes active, the differential signal
(which indicates the first peak of the double crested analog signal) starts
the timer. The second peak then stops the timer, if the gate signal
remained active for the duration between peaks.

Two PAL ICs (Programmable Array Logic Integrated Circuits) are also on
the digital module. The first PAL is the Address PAL, which is used to
record the time-of-flight data and side-scatter intensity.

The GATE and DIFF signals are also used to create two more signals, a
gate window signal and a zero cross signal, which are provided to the
Address PAL. The Address PAL uses these two signals to classify the
particle into 4 separate events, in all cases a gate window signal must be
present and at least one zero cross must occur.

Event 1

Occurs when only one zero cross occurs during a gate window. This
happens when the particle is bright enough to exceed the threshold on the
differential circuit when it intercepts one of the beams but not bright enough
to exceed the threshold when it intercepts the other.

Theory of Operation 5-7

Event 2

Detection
Threshold

Detection
Threshold

Detection
Threshold

4.096µs

Is a valid particle event and occurs only when two zero crosses happen
during a gate window. Both the time of flight and light-scatter intensity are
recorded for this event.

Event 3

Is a coincident event, and occurs when three zero crosses happen during a
gate window. This is caused by a second particle entering the
measurement area before the previous one has left.

Event 4

Is an over range event and occurs when a second zero cross does not
occur and the window does not go away until after the timer over-ranges,
exceeds 4.096 s. This happens when a very large particle or a
recirculating particle travels very slowly through the measurement area.

The second PAL is the Counting PAL, and is used by the address PAL to
record all events. Events 1, 3, and 4 each have their own location in
memory and are reported in the headers of the A, B, C, D, and S records.
The events are recorded in bins of the accumulator as reported in the A
record as follows: Event 1 in bin 32, Event 3 in bin 33, Event 4 in bin 34.
Event 2 can be totaled by adding bins 100 through 1023 of the
accumulator. Event 2 is recorded in memory according to the time of flight
reported. The side scatter intensity is also recorded for each Event 2.

The APS™ spectrometer can be configured to record data in two different
modes: uncorrelated and correlated.

5-8 Model 3321 Aerodynamic Particle Sizer Spectrometer

Uncorrelated Mode

The Address PAL creates two separate addresses. One address is 10 bits
and represents the type of event (1, 3, 4), or the time-of-flight (TOF) in the
case of an event 2. And the second address is 6 bits and represents the
light-scatter intensity for an event 2. There is no second address in the
case of an event 1, 3, or 4.

Correlated Mode

The Address PAL creates one single 16-bit address. The upper 10 bits of
the address are the time-of-flight (TOF) for an event 2 or the type of event
(1, 3, 4). The lower 6 bits are the side-scatter (SS) intensity in the case of
an event 2. For events 1, 3, 4, the lower bits are zero.

Once the address(es) are created, the address PAL loads the number of
particles from that address in memory into the counting PAL. The counting
PAL then increments the number by one and stores it back to the same
address. Once the PALs are finished recording the data, the timer is reset
for the next particle.

Particle Coincidence

Particle coincidence is typically defined as more than one particle in the
viewing volume of the particle counter creating a signal that causes the
counter to incorrectly classify the particles as a single, mis-sized particle.
Coincidence typically increases proportionally with particle concentration.
In the case of the Model 3321 APS™ spectrometer; however, although
coincidence is still a problem at high concentrations, the particles are not
mis-classified. The double-crested signal processing technique allows the
processor to determine when a signal is caused by a single low scattering
particle (event 1—see above) and when it is caused by coincidence (event
3—see above). This means that the particle size distribution during
coincidence can be accurately measured. Coincident particles can be
detected as event 3s, but cannot be sized. Therefore they are not included
in the size distribution, but are recorded for possible concentration
corrections.

Theory of Operation 5-9

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5-10 Model 3321 Aerodynamic Particle Sizer Spectrometer

C H A P T E R 6

Contacting Customer
Service

This chapter gives directions for contacting people at TSI Incorporated for
technical information and directions for returning the Model 3321
Aerodynamic Particle Sizer Spectrometer for service.

Technical Contacts

 If you have any difficulty setting up or operating the APS spectrometer,

or if you have technical or application questions about this system,
contact an applications engineer at one of the locations listed below.

TSI Incorporated
500 Cardigan Road
Shoreview, MN 55126 USA

Phone: [phone] (USA) or [phone]
E-mail: [e-mail]

TSI GmbH
Neuköllner Strasse 4
52068 Aachen
GERMANY

Telephone: [phone]
Fax: [phone]
E-mail: [e-mail]
Web: www.tsiinc.de

TSI Instruments Ltd.
Stirling Road
Cressex Business Park
High Wycombe, Bucks
HP12 3ST
UNITED KINGDOM

Telephone: [phone]
Fax: [phone]
E-mail: [e-mail]
Web: www.tsiinc.co.uk

6-1

Returning the APS Spectrometer for Service

Visit our website at http://rma.tsi.com or call TSI at 1-800-874-2811 (USA)
or [phone] for specific return instructions. Customer Service will
need this information when you call:

 The instrument model number
 The instrument serial number
 A purchase order number (unless under warranty)
 A billing address
 A shipping address

Use the original packing material to return the instrument to TSI. If you no
longer have the original packing material, seal off any ports to prevent
debris from entering the instrument and ensure that the display and the
connectors on the instrument front and back panels are protected.

6-2 Model 3321 Aerodynamic Particle Sizer Spectrometer

Maintenance Operation

Hours of Continuous

Operation

User/Factory

Cleaning Inner Nozzle

750

user

Cleaning Outer Nozzle

2500

user

Replace Air Filters

5000

user

Check/Update

Calibration

5000

user/factory

A P P E N D I X A

Maintenance

Most components of the APS™ spectrometer are solid state and require no
maintenance. This section provides information about the maintenance
procedures that are required and includes a suggested maintenance
schedule.

Maintenance Schedule

The following table contains a schedule of approximate recommended
intervals for maintenance. The conditions under which the instrument is
used will greatly affect this schedule. If the instrument is used to sample
unusually dirty environments, the times between maintenance should be
shortened. Likewise, if the instrument is used in clean environments, the
times between maintenance can be safely extended. Use the schedule as
a guideline only.

Table A-1
Maintenance Schedule

A-1

Cleaning the Inner Noz z le

W A R N I N G

Make sure power is switched off and power cord is disconnected to
avoid any exposure to hazardous laser radiation.

W A R N I N G

High voltage is accessible in several locations within this instrument.
Make sure you unplug the power source before removing the cover or
performing maintenance procedures.

C a u t i o n

The electronic circuits within this instrument are susceptible to electro­static discharge (ESD) damage. Use ESD precautions to avoid
damage.

 Use only a table top with a grounded conducting surface
 Wear a grounded, static-discharging wrist strap

Clean the nozzles according to the maintenance schedule and also under
the following circumstances:

 The flows in the instrument are too low or erratic
 The APS™ spectrometer has been exposed to extremely high aerosol

concentrations or fibers

 There is a constant level of particle noise even when the APS™

spectrometer samples filtered air

To clean the nozzles, proceed as follows:

1. Switch the power off using the switch on the back of the cabinet and
unplug the power cord from the APS™ spectrometer.

2. Remove the knurled retaining ring from the outer inlet nozzle.

3. Loosen the six screws on both sides of the cabinet (two turns is

sufficient) and remove the cover straight upward.

4. Remove the outer inlet nozzle by gripping it and lifting straight up.

5. Grip the inner nozzle and lift straight up.

6. Clean the nozzle blowing backward through the nozzle with clean,

compressed air [maximum pressure 35 psi (240 kPa)].

7. Check the nozzle by holding the tube up to a light and checking for a
clear view of the nozzle orifice.

8. If the nozzle is still blocked, try rinsing the inner nozzle in soapy water
and then cleaning with clean water. Dry thoroughly with clean
compressed air.

9. If the nozzle is still blocked, try using isopropyl alcohol.

A-2 Model 3321 Aerodynamic Particle Sizer Spectrometer

W A R N I N G

Make sure power is switched off and power cord is disconnected to
avoid any exposure to hazardous laser radiation.

W A R N I N G

High voltage is accessible in several locations within this instrument.
Make sure you unplug the power source before removing the cover or
performing maintenance procedures.

10. When the nozzle has been cleaned satisfactorily, make sure that the
o-ring still has a thin layer of grease. If not, apply a thin coating of
grease.

11. Reinsert the nozzle and make sure that it is seated firmly in the
nozzle mount.

12. Replace the outer inlet in the nozzle mount. Note that there is an
alignment pin that matches a slot in the side of the outer inlet. Rotate
the outer inlet until the inlet seats on the alignment pin.

13. Replace the cover on the instrument.

14. Tighten the six screws holding the cover in place.

15. Replace the outer inlet retaining ring and tighten firmly.

16. Insert the power cord into the power entry connector on the back of

the instrument.

17. Apply power to the instrument with the switch on the back panel.

18. Check that the flows are correct.

Cleaning the Outer N o z zle

Clean the nozzles according to the maintenance schedule and also under
the following circumstances:

 The pumps are running at maximum flow and the nozzle flow is still too

low

 The APS™ spectrometer has been exposed to extremely high aerosol

concentrations or to fibers

 There is a constant level of particle noise even when the APS™

spectrometer samples filtered air

To clean the nozzles, proceed as follows:

Maintenance A-3

C a u t i o n

The electronic circuits within this instrument are susceptible to electro­static discharge (ESD) damage. Use ESD precautions to avoid
damage.

 Use only a table top with a grounded conducting surface
 Wear a grounded, static-discharging wrist strap

C a u t i o n

Any time that you remove a portion of the optics assembly for cleaning,
there is a chance that you can adversely affect the alignment of the
system and therefore the calibration. It is a good idea to check the
calibration of the instrument after any procedure involving the optics. Do
this by generating a know size of aerosol, ie. 1 µm polystyrene latex
(PSL) and making sure that the aerosol is sized correctly by the
instrument and software.

1. Switch the power off using the switch on the back of the cabinet and
unplug the power cord from the APS™ spectrometer.

2. Remove the knurled retaining ring from the outer inlet nozzle.

3. Loosen the six screws on both sides of the cabinet (two turns is

sufficient) and remove the cover straight upward.

4. Remove the outer inlet nozzle by gripping it and lifting straight up.

5. Grip the inner nozzle and lift straight up.

6. Remove the two screws securing the digital printed circuit board.

7. Tilt the printed circuit board upward and remove the large ribbon

cable connector from the center front of the board.

8. Tilt the printed circuit board all the way back so that the pumps are
visible and the board rests against the top edge of the back of the
instrument.

9. Label the two tubes coming from the nozzle mount and going to the
pumps (a fine-tip permanent marker works well). Label the top tube
“top” and the bottom tube “bottom”.

10. Grip each tube and remove it from the nipple fitting attached to the
nozzle mount.

11. Loosen the knurled retaining ring at the base of the nozzle mount.

12. Lift the nozzle mount away from the optics block taking care not to

scratch or damage the delicate outer nozzle. Make sure that the O­ring under the nozzle mount stays with the optics block.

Note: The outer nozzle is very delicate. Take great care in cleaning or

blowing compressed air through the nozzle.

13. Blow clean, compressed air backwards through the outer nozzle to
remove any debris.

A-4 Model 3321 Aerodynamic Particle Sizer Spectrometer

14. The finish on the outside of the nozzle should be flat black. Remove
any coating on the outer nozzle with a clean, lint-free, soft cloth and
clean water.

15. Check that the nozzle is clear by holding it up to a light and checking
for a clear view through the nozzle orifice.

16. It is not recommended that you clean the inside of the outer nozzle
with other than clean compressed air. Using a swab to clean may
result in leaving difficult-to-remove fibers inside the nozzle or
damaging the inner nozzle centering ring.

17. Reinsert the nozzle block into the optics block. The nozzle block has
a slot that aligns with a pin in the optics block. Tighten the retaining
ring so that the nozzle block can still rotate freely. Rotate the nozzle
until the pin catches the slot in the nozzle. Tighten the retaining ring
until the nozzle block is firmly seated.

18. Reinsert the inner nozzle and make sure that it is seated firmly in the
nozzle housing.

19. Reattach the tubing to the nozzle mount, noting the labels on each
tube.

20. Tilt the digital printed circuit board back down until the ribbon cable
connector can be plugged back into the board. Plug in the ribbon
cable connector.

21. Tilt the digital printed circuit board down fully and fasten with the
screws provided.

22. Replace the outer inlet in the nozzle mount. Note that there is an
alignment pin that matches a slot in the side of the outer inlet. Rotate
the outer inlet until the inlet seats on the alignment pin.

23. Replace the cover on the instrument.

24. Tighten the six screws holding the cover in place.

25. Replace the outer inlet retaining ring and tighten firmly.

26. Insert the power cord into the power entry connector on the back of

the instrument.

27. Apply power to the instrument with the switch on the back panel.

28. Check that the flows are correct.

29. Generate a known size of monodisperse aerosol (such as

Polystyrene latex–PSL) and make sure that the calibration has not
been altered by the cleaning procedure.

30. If the instrument does not size correctly, check the parts you have
cleaned and make sure that they are assembled correctly: alignment
pins in slots and retaining rings holding parts seated firmly.

31. If the instrument still does not size correctly, it may have to be
recalibrated.

Maintenance A-5

Replacing the Filters

W A R N I N G

Make sure power is switched off and power cord is disconnected to
avoid any exposure to hazardous laser radiation.

W A R N I N G

High voltage is accessible in several locations within this instrument.
Make sure you unplug the power source before removing the cover or
performing maintenance procedures.

C a u t i o n

The electronic circuits within this instrument are susceptible to electro­static discharge (ESD) damage. Use ESD precautions to avoid
damage.

 Use only a table top with a grounded conducting surface
 Wear a grounded, static-discharging wrist strap

Replace the four filters (TSI P/N 1602230) according to the maintenance
schedule and under the following circumstances:

 If the pumps are at maximum power and still cannot achieve the

correct flows for the instrument

 If the flow path has become wetted by any kind of liquid

To replace the filters, proceed as follows:

1. Switch the power off using the switch on the back of the cabinet and
unplug the power cord from the APS™ spectrometer.

2. Remove the knurled retaining ring from the outer inlet nozzle.

3. Loosen the six screws on both sides of the cabinet (two turns is

sufficient) and remove the cover straight upward.

4. Remove the two screws securing the digital printed circuit board.

5. Tilt the printed circuit board upward and remove the large ribbon

cable connector from the center front of the board.

6. Tilt the printed circuit board all the way back so that the pumps are
visible and the board rests against the top edge of the back of the
instrument.

7. The APS™ spectrometer contains a lot of tubing. To easily keep track
of the connections, disconnect the tubing from one filter at a time and
replace it, rather than disconnecting all tubing at once. Also, make
note of the direction of the flow arrow on the filter before
disconnecting it.

8. Lift up on a filter so that it comes out of its supporting clip.

A-6 Model 3321 Aerodynamic Particle Sizer Spectrometer

W A R N I N G

Make sure power is switched off and power cord is disconnected to
avoid any exposure to hazardous laser radiation.

W A R N I N G

High voltage is accessible in several locations within this instrument.
Make sure you unplug the power source before removing the cover or
performing maintenance procedures.

C a u t i o n

The electronic circuits within this instrument are susceptible to electro­static discharge (ESD) damage. Use ESD precautions to avoid
damage.

 Use only a table top with a grounded conducting surface
 Wear a grounded, static-discharging wrist strap

9. Remove the tubing from each end by pushing the tubing from its end
off of the filter rather than pulling the tubing off.

10. If any of the tubing becomes damaged, replace it with an equivalent
length of the same tubing.

11. Snap the filter back into its holding clip.

12. Replace each filter in turn until all four have been replaced.

13. Tilt the digital printed circuit board back down until the ribbon cable

connector can be plugged back into the board. Plug in the ribbon
cable connector.

14. Tilt the digital printed circuit board down fully and fasten with the
screws provided.

15. Replace the cover on the instrument.

16. Tighten the six screws holding the cover in place.

17. Replace the outer inlet retaining ring and tighten firmly.

18. Insert the power cord into the power entry connector on the back of

the instrument.

19. Apply power to the instrument with the switch on the rear panel.

20. Check that the flows are correct.

Replacing the EPROM

Normally the EPROM will not be replaced, however, early shipments of the
Model 3321 APS™ spectrometer may not have all functions/features in
place and therefore EPROM replacement will be necessary in the field.

To replace the EPROM, proceed as follows:

Maintenance A-7

1. Switch the power off using the switch on the back of the cabinet and
unplug the power cord from the APS™ spectrometer.

2. Remove the knurled retaining ring from the outer inlet nozzle.

3. Loosen the six screws on both sides of the cabinet (two turns is

sufficient) and remove the cover straight upward.

4. Remove the two screws securing the digital printed circuit board.

5. Tilt the printed circuit board all the way back so that the pumps are

visible and the board rests against the top edge of the back of the
instrument.

6. The APS™ spectrometer uses two EPROM chips. They should be
labeled with seven digit part numbers. It is important that they go in
the correct sockets.

7. Locate the EPROM sockets from Figure A-1.

Figure A-1

Location of EPROM Chips on APS™ Spectrometer Digital PC-Board

8. Use the EPROM removal tool provided with the new EPROM chips to
remove one of the old chips.

9. Remove the new EPROM with the same seven-digit part number
from its static protection bag

10. Install the new chip into the vacant socket by aligning the notch on
the top center of the chip with the notch shown on the silkscreen.

11. Then, while supporting the printed circuit board with one hand behind
it, slightly insert one row of pins and then the other.

12. Once both rows of pins are slightly inserted, press the EPROM firmly
the rest of the way into the socket.

A-8 Model 3321 Aerodynamic Particle Sizer Spectrometer

13. Inspect the socket to make sure that all pins are inserted into the
socket.

14. Repeat steps 8 to 13 to replace the remaining EPROM.

15. Tilt the digital printed circuit board back down until the ribbon cable

connector can be plugged back into the board. Plug in the ribbon
cable connector.

16. Tilt the digital printed circuit board down fully and fasten with the
screws provided.

17. Replace the cover on the instrument.

18. Tighten the six screws holding the cover in place.

19. Replace the outer inlet retaining ring and tighten firmly.

20. Insert the power cord into the power entry connector on the back of

the instrument.

21. Apply power to the instrument with the switch on the back panel.

22. Check that the version shown on the screen on startup matches the

new version of the EPROM.

Calibrating the AP STM Spectrometer

Calibrating the APS™ spectrometer is a fairly complex procedure. The
calibration process requires special equipment and tools. Therefore, it is
recommended you return the instrument to the factory for calibration.

Maintenance A-9

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A-10 Model 3321 Aerodynamic Particle Sizer Spectrometer

Symptoms

Recommendations

The pumps do not come on when the
instrument is powered up

Check to see that the pumps are turned on from the front panel menu.
Rotate the control knob all the way clockwise until the menu button is shown. Press

the control knob in so that the menu appears.
Rotate the knob to scroll the cursor down the menu until the pumps item is

highlighted.
Press the control knob to toggle the pumps on and off.
Exit the menu.
If the pumps are off when you exit the menu, the APS™ spectrometer will not start

them on power-up. If they are on when you exit the menu, they will turn on when
the APS™ spectrometer is powered up.

The pumps do not control the flows to
the proper flow rates or the flows are
erratic

Check for blockage in the flow path:
The outlet in the back panel may be blocked or covered. Check and clear any

obstruction.
The inner or outer nozzle may be dirty or clogged. See Appendix A, “Maintenance.”
The filters may be clogged. See Appendix A, “Maintenance.”

The HI CONC (High concentration)
warning light is illuminated

The HI CONC LED is an indicator that the concentration of aerosol that the
instrument is sampling is too high for the APS™ spectrometer to accurately
measure. The LED is lit when the concentration exceeds 1000 particles/cm3.
Although the APS™ spectrometer can measure aerosols at concentrations greater
than this value, concentration errors due to coincidence will increase and some of
the particles will not be counted. To correct this problem, reduce the concentration
of the sampled aerosol (by mixing filtered air with the sample, for instance) or use
one or two diluters (TSI Model 3302A) with the APS™ spectrometer.

A P P E N D I X B

Troubleshooting

This appendix lists potential problems and their solutions.

Note: If none of the solutions provided corrects the problem, call your TSI

representative for advice.

Table B-1
Troubleshooting Symptoms and Recommendations

B-1

Symptoms

Recommendations

The LASER LED does not come on
when the instrument is powered up

Check to see that the laser is turned on from the front panel menu.
Rotate the control knob all the way clockwise until the menu button is shown. Press

the control knob in so that the menu appears.
Rotate the knob to scroll the cursor down the menu until the laser power item is

highlighted.
Make sure that the setting is 50% or higher (factory setting is 75%). Note:

changing the power setting from the instrument calibration setting will change the
calibration.

Rotate the knob to scroll the cursor down the menu until the laser item is
highlighted.

Press the control knob to toggle the laser on if necessary.
Exit the menu.
If the laser is off when you exit the menu, the APS™ spectrometer will not turn it on

at power-up. If it is on when you exit the menu, it will turn on when the APS™
spectrometer is powered up.

No power

Check for good contact between the power cord and the wall outlet. Check for
power at the outlet.

Serial Communications not working

See Table C-4, “Troubleshooting Serial Commands.”

B-2 Model 3321 Aerodynamic Particle Sizer Spectrometer

5 4 3 2 1

9 8 7 6

A P P E N D I X C

Using Serial Data
Commands

This chapter contains information you need if you are writing your own
software for a computer or data acquisition system. Information includes:

 Pin connectors
 Baud rate
 Parity
 Command definitions and syntax.
 Examples, as well as input and troubleshooting directions are also

provided.

Pin Connectors

The Model 3321 has a single 9-pin, D-subminiature connector port on the
back panel labeled SERIAL PORT (See Figure 3-3 and Figure C-1). This
communication port is configured at the factory to work with RS-232 type
devices. Table C-1 provides the signal connections.

Figure C-1
SERIAL PORT Pin Designations

C-1

Baud Rate

Table C-1

Signal Connections for RS-232 Configurations

Pin Number RS-232 Signal

1 —
2 Transmit Output
3 Receive Input
4 —
5 GND
6 —
7 —
8 —
9 —

The baud-rate setting is the rate of communication in terms of bits per
second (baud). The Model 3321 uses a baud rate setting of 9600, 19,200
or 38,400. For proper communications, make sure that all software used
with the instrument is set at the appropriate rate. The baud-rate must be
set to 38,400 for correlated mode. See SMT and SB commands.

Parity (7-Bits E v en)

Parity is the additional bit that accompanies the seven data bits to confirm
that they are transmitted correctly. It is set so that the number of “1” data
bits (high) in a transmitted character is always an even number. The Model
3321 APS™ spectrometer uses even parity as the only setting.

Stop Bits and Flow C o ntrol

The APS™ spectrometer uses a Stop bits setting of 1 and a Flow Control
Setting of None.

C-2 Model 3321 Aerodynamic Particle Sizer Spectrometer

Commands

The Model 3321 APS™ spectrometer uses an ASCII-based
communications protocol that uses the RS-232 port of a computer to
transmit commands in the form of strings.

The four types of commands are:

 Set commands, which set all the operating parameters for the APS™

spectrometer

 Action commands, which control mechanical components of the APS™

spectrometer

 Read (polled) commands, in which the APS™ spectrometer sends data

in response to a specific request from the computer

 Unpolled commands, in which the APS™ spectrometer automatically

outputs data records at specific intervals.

No line-feed characters are transmitted. Either the requested data or an

"OK" is returned if the command is understood. The word “ERROR” is

returned if the command is not understood or if the command has an
invalid parameter.

Note: All characters must be UPPERCASE.

The following tables (Figure C-2) provide a quick reference to all the serial
commands. Command definitions, syntax, and examples begin after the
tables. Directions for issuing commands and troubleshooting commands
are provided at the end of this section.

(continued on next page)

Using Serial Data Commands C-3

SB

SCA

SCL
SCE

SCR

SD

SF

SH

SL

SMA

SMC

SMT

SP

STU

SV

Set Baud rate

SBx

Set Calibration for Aerodynamic diameters

SCAc,sc,tc

Set Calibration Label string
Set Calibration Environment

SCEp,t

Set Calibration Resolution

SCRx

Set Digital output

SDx

Set Front panel enable

SFx

Set Hi Conc threshold

SHx

Set Laser power

SLx

Set Mode for Analog output

SMAx

Set Mode for automatic Calibration of APD

SMCx

Set Mode and sample Time

SMTa,t

Set Pumps

SPx

Set Time for Unpolled report

STUx

Set analog output Voltage

SVx

A
B

C
D
F

G

H
L
Q
S

Autocal the APD
Beep

Bx
Clear buffers and sample time
Dump command
Fill command

Fx
Go (sample)

Gx
Halt command
Laser on/off
Quick concentration report
Sampling

Sx

R

RF
RI

RL
RO

RPI
RPS
RPT
RQA
RQS
RQT
RR

RTB
RTD
RTI
RV

Read accumulator

Rb,e
Read status Flags
Read Input from pins 1, 2, 3 and 7, 8 of the

I/O connector
Read Laser power
Read accumulated On time of instrument
Read inlet pressure
Read sheath delta P
Read total delta P
Read aerosol flow
Read sheath flow
Read total flow
Read Unpolled Record
Read Temperature in Box
Read Temperature of APD Detector
Read Temperature of Inlet
Read Version of firmware

U
U+
U­UA

UB

UC

UD

US

UY

Unpolled operation begins
Enable all records
Disable all records
Accumulator record

UA0/1
SS accumulator record

UB0/1
Correlated (paired) records

UC0/1
Aerodynamic data record

UD0/1

SS data record

US0/1
Auxiliary data record

UY0/1

Set Commands

Read (Polled) Commands

Unpolled Commands

Action Commands

C-4 Model 3321 Aerodynamic Particle Sizer® Spectrometer

Figure C-2

Serial Command Tables

Set Commands

Set commands allow you to set up operating parameters for the Model

3321. If a set command is sent with no parameter, the current parameter is
echoed.

Note: Some of the commands directly affect or are affected by other

SB—Set Baud Rate

SB lets you set and change the baud rate for the serial communications.

Note: Since this is changed with serial communication, once sent, the

The baud rate can also be changed from the APS™ spectrometer front
panel menu, see Table 4-1.

where:

Examples:

commands. Refer to other commands where indicated.

baud rate of the application sending commands must be changed to
match baud rates or communications will fail.

SBx

x = 0 for 9,600
1 for 19,200
2 for 38,400

To se the baud rate to 38,400:

SB2

Note: “OK” is sent in response to this command, but it is sent at the new

baud rate and is not readable at the previous baud rate. You must
now change your application baud rate to 38,400 in order to
communicate with the APS™ spectrometer.

SCA—Set Calibration for Aerodynamic Diameters

SCA lets you enter calibration data for time of flight data (aerodynamic
calibration).

SCAc,sc,tc

where:

c = channel boundary number (0 to number of channels +1).
sc = particle size in nm.
tc = time of flight for the boundary of the particle size channel.

Using Serial Data Commands C-5

The number of channels must be at least 1 (3 calibration records: lower
size, upper size, and terminator) and no more than 52 (54 calibration
records). The time values correspond to accumulator time. They must be
between 0.00 and 1024.00. The value 0,0 terminates the calibration array.
There can be up to 52 channels of particle size requiring 54 calibration
points SCA0 to SCA53. The last entry of any calibration table must be 0,0.
The calibration data is held in EEPROM and loaded into RAM on power up.
The SCA0,0 terminator also causes the calibration data to be tested for
monotonicity and if the data in the calibration table is not monotonic returns
an error message “NOTVALID.”

Examples:

To set the lower boundary of the first channel to 403 nm bin 187.63:

SCA0,403,187.63

To terminate the calibration array of 52 channels:

SCA53,0,0

To echo the current calibration:

SCA

SCL—Set Calibration Label String

SCL lets you label a calibration with a text string (up to 80 characters).

Example:

To label the calibration done on December 25th of the APSTM spectrometer
with serial number 104:

SCLS/N 104 Calibrated December 25, 1997

C-6 Model 3321 Aerodynamic Particle Sizer Spectrometer

SCE—Set Calibration Environment

SCE lets you set the temperature and pressure.

SCEp,t

where:

p = absolute pressure at calibration (in millibars).
t = absolute temperature at calibration (in degrees K).

SCE with no parameters echoes the current values of p and t, which are
saved in EEPROM and loaded into RAM when the instrument is powered
up.

Example:

To set the absolute pressure and temperature to 970.4 millibar and

393.3 K:

SCE970.4,393.3

SCR—Set Calibration Resolution

SCR lets you set the number of side scatter channels that will report.

SCRx

where:

x = 1, 2, 4, 8, 16, 32, or 64.

Note: 64 is the default on power up.

Example:

To set the number of side scatter channels that will report to 16:

SCR16

SD—Set Digital Output

SD sets the logic level of the three digital I/O connector output pins 11, 12,
and 13. (See Figure 3-3, Figure 3-5, and Table 3-2 for the location and
pinout of I/O Port on back panel. (Referenced to pins 4, 5 Digital GND.)

SDh

where:

h = 0 to 7 and is a hex value representing three binary bits. If a bit is 0,

the corresponding output is set to 0 volts. If a bit is a 1, the output
is set to 5 volts.

Table C-2 shows the equivalent voltage level (in volts) of pins 11, 12, and
13 for all possible settings.

Using Serial Data Commands C-7

Hex Setting
(h)

Binary
Equivalent

Pin 13

Pin 12

Pin 11

0

000 0 0 0 1

001 0 0 5 2

010 0 5 0 3

011 0 5 5 4

100 5 0 0 5

101 5 0 5 6

110 5 5 0 7

111 5 5

5

Table C-2

Digital Output Pin Settings

Example:

To set the outputs for I/O connector pins 11, 12, and 13 to 0 volts:

SD0

To set the outputs for I/O connector pins 11, 12, and 13 to 5 volts:

SD7

SF—Set Front Panel Enable

SF lets you disable the front panel of the Model 3321 to prevent clearing
sample averages that are being read by an external computer.

SFx

where:

x = 0 or 1:
0 = front panel disabled
1 = front panel enabled

When the front panel is disabled, it has “view only” control. You can read

front panel settings, but no modification is allowed. The default is 1 when
the instrument is powered on. The parameter is not stored in EEPROM so
the panel is always enabled on startup.

Example:

To disable the front panel of the 3321:

SF0

C-8 Model 3321 Aerodynamic Particle Sizer Spectrometer

SH—Set Hi Conc Threshold

SH lets you set the conditions that will cause the HI CONC LED to light, the
high concentration flag to be set (see RF command), and the APS™
spectrometer to beep if the sound is enabled (see B command).

SHx

where:

x = 0 to 65535 and is the total concentration of particles, in particles/cm3.

Note When x =0, the LED, flag, and beep are always on. When x =

65535, the LED, flag, and beep are always off.

The value of x at power up is 1000 particles/cm3. The status of the LED is
updated every second.

Examples:

To light the HI CONC LED when the concentration 1500 particles/cm3:

SH1500

To prevent the HI CONC LED from lighting at any concentration:

SH65535

SL—Set Laser Power

SL sets the laser power as a percent of full-power.

SLx

where:

x = 0 to 100%

The default when the instrument is powered up is 75%.

Example:

To set the laser power to 50 percent of full power:

SL50

Notes:

 Lx command must be Enabled (x = 1) for laser to output power (see Lx

command).

 An SL setting <10 may cause Laser LED on front panel to flash (see

Chapter 3, “Indicators”).

 Front panel LED may flash if laser is not able to operate at set power.

This indicates that the laser has degraded and may need to be
replaced.

Using Serial Data Commands C-9

Table C-3

SMA
Setting

BNC Analog Output Voltage (V)

X

0 1 2 3 4 5 10 0 0

.1/cc

.2/cc

.3/cc

.4/cc

.5/cc

1/cc 1 0

1/cc

2/cc

3/cc

4/cc

5/cc

10/cc

2

0

10/cc

20/cc

30/cc

40/cc

50/cc

100/cc

3

0

100/cc

200/cc

300/cc

400/cc

500/cc

1000/cc

4

0

1000/cc

2000/cc

3000/cc

4000/cc

5000/cc

10,000/cc

5

.1/cc

1/cc

10/cc

100/cc

1000/cc

10,000/cc

NA 6 0

1v

2v

3v

4v

5v

10v

Analog Voltage Output Settings

SMA—Set Mode for Analog Output

SMA sets the mode and range for the analog output BNC on the back
panel

SMAx

where:

x = 0 to 6
0 = total concentration 1/cc 10 volts.

1 = total concentration 10/cc 10 volts.
2 = total concentration 100/cc 10 volts.
3 = total concentration 1,000/cc 10 volts.
4 = total concentration 10,000/cc 10 volts.
5 = total concentration Log 10,000/cc 5 volts.
1,000/cc 4 volts
100/cc 3 volts
10/cc 2 volts
1/cc 1 volts
.1/cc 0 volts
6 = host.

Examples:

To set the analog output BNC voltage range 0–10 volts, to represent the
total concentration range 0–10,000 particles/cc.

SMA4

To set the analog output BNC to host mode. (See the SV command for the
actual voltage output.)

SMA6

C-10 Model 3321 Aerodynamic Particle Sizer Spectrometer

SMC—Set Mode for Automatic Calibration of APD

SMC lets you set the mode for automatically calibrating the Avalanche
photodetector (APD) for temperature based reading of RTD command.

SMCx

where:

x = 0 or 1
0 means that autocal is disabled.

1 means that autocal is enabled.

Example:

To enable automatic calibration of the APD:

SMC1

Default at power up = autocal is enabled

SMT—Set Mode and Sample Time

SMT lets you set the sample mode and sample time for continuous
sampling operation. See S command for more details on starting/stopping
sampling according to SMT command.

SMTa,t

where:

a = sample mode
0 means averaging mode

1 means summing mode
2 means correlated data (paired) mode

t = sample time in seconds
1 to 300 seconds if averaging mode is set

1 to 65535 seconds if summing mode or correlated data (paired) mode is
set

Note: The value of t is saved in EEPROM and loaded when the

instrument is powered up.

Examples:

To set the sample mode to averaging and the sample time to 240 seconds:

SMT0,240

To set the sample mode to summing and the sample time to 12 hours:

SMT1,43200

Using Serial Data Commands C-11

To set the sample mode to correlated data (paired) and the sample time to
60 minutes:

SMT2,3600

Note: Baud rate must be set to 38,400 for correlated mode. See SB

command. Baud rate can also be set from the front panel menu
(see Table 4-1).

SP—Set Pumps

SP lets you turn the pumps on and off.

Spx,y

where:

x = total pump status (0 = off, 1 = on)
y = sheath pump status (0 = off, 1 = on)

Note: Turn both pumps on with SP1. Turn both pumps off with SP0.

Examples:

To set the total pump off and the sheath pump on:

SP0,1

To set the total pump on and the sheath pump off:

SP1,0

STU—Set Time for Unpolled Report

STU lets you set the time for unpolled reports. End of sample reports are
sent regardless of the STU setting.

STUx

where:

x = 0 to 65535 seconds

Example:

To set the time for unpolled reports to 3600 seconds:

STU3600

C-12 Model 3321 Aerodynamic Particle Sizer Spectrometer

SV—Set Analog Output Voltage

SV sets the analog output BNC voltage when configured for host mode.
See SMA command.

SVx

where:

x = 0 to 10,000 mV

Example:

To set the analog output voltage to 2400 millivolts or 2.4 volts:

SV2400

Action Commands

Action commands control mechanical components of the Model 3321. If
you enter an action command without a parameter, the mechanical state is
echoed back.

A—Perform APD Autocal

Performs an automatic calibration of the Avalanche Photodetector if
autocal is enable by the SMC command, see SMC.

Example:

To perform automatic calibration of the APD:

A

B—Beep

Bx,y

where:

x = no value, 0, 1, >1.
no value for x returns 1 if beep is active, 0 if not. A 0 turns beep off; a 1
turns beep on. >1 is number of beeps.
y = duration of beep in approximately 62.5 ms steps (for a 1-second
beep, y = 16). If no y is given and x is >1, the beep will have a 1
second duration.

Note: Beep must be active, B1, to hear beeps. State of beep is stored.

Single beeps require a value for y.

Using Serial Data Commands C-13

C—Clear Buffer and Sample Time

Clears the buffer, accumulator, and sample time setting. Appends a line
feed (LF) character after the terminating carriage return (CR). Used only in
3310 APS™ spectrometer mode. Refer to the G command.

D—Dump

Performs a dump or all 78 channels (3310 APS™ spectrometer type). Data
beyond SCA calibration (max. of 52 channels), is reported as 0. Appends a
LF character after the terminating CR.

F—Fill Accumulators

Fills accumulators with x. If no x is provided it returns 1 or 0 to indicate
active or inactive. When active, an S1 command begins a sample of SMT
time and fill data is not cleared after each one second summation. If x=0,
then fill is disabled and data can be cleared. The pumps should be off or a
filter in place to prevent particles from being added to the fill data.

Fx

where:

x is 1–65535, but typically 10.

G—Go

Enables a 3310 mode sample.

Gx

where:

x is 1 to 65565 seconds of sample time.

In 3310 mode, the APS™ spectrometer runs without side-scatter and
acquires accumulator data. The command appends a LF after the
terminating CR.

H—Halt

Halts the 3310 mode. The command appends a LF after the terminating
CR.

C-14 Model 3321 Aerodynamic Particle Sizer Spectrometer

L—Laser Enable/Disable

Enables or disables the laser.

Lx

where:

x is 0 or 1. L0 Disables the laser. Output power is 0. L1 Enables the
laser. Output power is determined by the SL setting (see SL command).

Q—Quick Concentration Report

Produces a concentration report. This is a 3310 command. A LF is
appended after the terminating CR.

S—Sampling

Enables and disables sampling. (The mode of sampling is set by the SMT
command.)

Sx

where:

x is 0, 1 or 2 through 65565.
0 = Disable sampling.
1 = Enable continuous sampling. (Previous sample data automatically
cleared when new sample begins.)
2 - 65565 = Enable a single sample for x seconds. (If SMT is set to
average mode, a summed sample will be done. Previous data is not
automatically cleared and must be cleared with the C command.)

If no parameter is specified, the command echoes current condition (0, 1 or
sample time remaining if single sample is running). The default when the
instrument is powered up is 0.

Using Serial Data Commands C-15

Read Commands (Polled)

Read commands are polled, which means the Model 3321 sends data in
response to a specific request from the computer

R—Read Accumulator

This is a 3310 mode command. It dumps accumulator data taken using a G
command.

Rb,e

where:

b = the beginning accumulator bin (0-1023).
e = the ending accumulator bin (0-1023). e must be greater than or equal

to b.

If b and e are not specified, the default values are b = 0 and e = 1023. Line
feeds are appended after all carriage returns.

Example Response

R0,100 Reads bins 0 to 100
R,100 Reads bins 0 to 100
R400 Reads bins 400 to 1023
R Reads bins 0 to 1023

RF—Read Flags

RF returns a four-character hexadecimal value representing the state of
the Model 3321.

The values for the 10 flags are as follows:

0000 0000 0000 0001 Laser fault
0000 0000 0000 0010 Total Flow out of range
0000 0000 0000 0100 Sheath Flow out of range
0000 0000 0000 1000 Excessive sample concentration (alarm)
0000 0000 0001 0000 Accumulator clipped (i.e. > 65535)
0000 0000 0010 0000 Autocal failed
0000 0000 0100 0000 Internal temperature < 10°C
0000 0000 1000 0000 Internal temperature > 40°C
0000 0001 0000 0000 Detector voltage more than ±10% Vb
0000 0010 0000 0000 Reserved (unused)

C-16 Model 3321 Aerodynamic Particle Sizer Spectrometer

Example Response

RF 00AC

00AC can be converted to binary: 0000 0000 1010 1100
This indicates that:

Internal temperature is greater than 40°C
Autocal failed
Excessive sample concentration
Sheath flow out of range

RI—Read Input From Pins 1, 2, 3 and 7, 8 of the I/O Connector

Pins 1, 2, and 3 are digital inputs and are reported as a binary number 000
to 111, where a 1 indicates 5 VDC level on the pin. (Digital ground pins for
the inputs are 9 and 10.) Pins 7 and 8 are analog inputs referenced to pin
15 analog ground. The analog values are reported as a decimal number
from 0.0 to 5.000 VDC. All readings are instantaneous.

Example Response

RI 100,2.43,1.93

Pin 1 has logic level high (5 VDC). Pins 2 and 3 are logic level low (0
VDC). Pin 7 is 2.43 VDC. Pin 8 is 1.93 VDC.

RL—Read Laser Power

Reads the current laser power output in percentage (%) of maximum
milliwatts and current in milliamps (ma)

Example Response

RL 75.0, 65.3

Indicates the laser power output is 75 percent of maximum output and
current is 65.3 ma.

RO—Read Accumulated On Time

Reads the accumulated on-time of the instrument (in hours). The time is
updated once an hour and stored in EEROM.

Example Response

RO 72

Indicates the Model 3321 has been on for approximately 72 hours.

Using Serial Data Commands C-17

RPI—Read Inlet Pressure

Reads the current absolute inlet pressure in millibars.

Example Response

RPB 1013.3

RPS—Read Sheath Delta P

Reads the change in pressure across the sheath flow orifice in Pascals.

Example Response

RPS 117.29

RPT—Read Total Delta P

Reads the change in pressure across the nozzle flow orifice in Pascals.

Example Response

RPT 130.72

RQA—Read Aerosol Sample Flow

Reads the aerosol sample flow rate in liters per minute (L/min). This is total
flow rate minus sheath flow rate.

Example Response

RQA 1.04

RQS—Read Sheath Flow

Reads the sheath flow rate in liters per minute (L/min).

Example Response

RQS 3.96

RQT—Read Total Flow

Reads the total flow rate in liters per minute (L/min).

Example Response

RQT 5.02

C-18 Model 3321 Aerodynamic Particle Sizer Spectrometer

RR—Read Record

Reads records A, B, C, D, S or Y. See description of records in following
subsection.

RRx

where:

x = A, B, C, D, S, or Y records

Note: To read C record, you must be in correlated mode (see SMT

command).

Example Response

RRA Record A is returned.

RTB—Read Temperature in Box

Reads the internal temperature of the Model 3321.

Example Response

RTB 298.2

Indicates the internal temperature is 298.2 K or 25.0° C.

RTD—Read Temperature of Detector (APD)

Reads the APD and optics temperature of the Model 3321.

Example Response

RTD 306.6

Indicates the APD and optics temperature is 306.6 K or 33.4° C.

RTI—Read Temperature of Inlet

Reads the inlet temperature constant of the Model 3321. This constant is
used for flow control only and is fixed.

Example Response

RTI 294.7

Indicates the inlet temperature is 294.7 K or 21.5°C.

Using Serial Data Commands C-19

RV—Read Firmware Version

Reads the current version level of the Model 3321 firmware.

Example Response

RV Model 3321 APS Firmware Version 1.12 13-Dec-

2001

Unpolled Comm a n ds

Using unpolled commands instructs the Model 3321 to automatically output
data records at specific intervals. In unpolled mode, 0 disables a record
and 1 enables the record. During unpolled operation, records that have
been enabled are sent at the end of each averaging time. All U parameters
are retained in EEPROM. Not all records available in all modes (e.g. UAx
command is not available in correlated mode and may return ERROR).

U—Begin Unpolled Operation

Enables and disables unpolled operation.

Ux

where:

x is 0 or 1.

U1 enables unpolled operation and clears continuous running average
buffers. U0 disables unpolled operation.

U+ —Enable All Records

Enables all unpolled records. See Data Records in the "Unpolled Record

Formats" section of this chapter.

U- —Disable All Records

Disables all unpolled records.

C-20 Model 3321 Aerodynamic Particle Sizer Spectrometer

UA—Generate Accumulator Report Record (Report Record A)

Enables and disables reporting of Record A in unpolled operation.

UAx

where:

x = 1 Enables A Record

x = 0 Disables A Record
UA will echo current setting 0 or 1.
See Record A in the “Unpolled Record Formats” section of this chapter.

UB—Generate Side Scatter Accumulator Report Record (Report Record B)

Enables and disables reporting of Record B in unpolled operation.

UBx

where:

x = 1 Enables B Record

x = 0 Disables B Record
UB will echo current setting 0 or 1.
See Record B in the “Unpolled Record Formats” section of this chapter.

UC—Generate Correlated (Paired) Report Record (Report Record C)

Enables and disables reporting of Record C in unpolled operation.

UCx

where:

x = 1 Enables C Record

x = 0 Disables C Record
UC will echo current setting 0 or 1.
See Record C in the “Unpolled Record Formats” section of this chapter.

Using Serial Data Commands C-21

UD—Generate Aerodynamic Data Report Record (Report Record D)

Enables and disables reporting of Record D in unpolled operation.

UDx

where:

x = 1 Enables D Record

x = 0 Disables D Record
UD will echo current setting 0 or 1.
See Record D in the “Unpolled Record Formats” section of this chapter.

US—Generate Side Scatter Data Report Record (Report Record S)

Enables and disables reporting of Record S in unpolled operation.

USx

where:

x = 1 Enables S Record

x = 0 Disables S Record
US will echo current setting 0 or 1.
See Record S in the “Unpolled Record Formats” section of this chapter.

UY—Generate Auxiliary Report Record (Report Record Y)

Enables and disables reporting of Record Y in unpolled operation.

UYx

where:

x = 1 Enables Y Record

x = 0 Disables Y Record
UY will echo current setting 0 or 1.
See Record Y in the “Unpolled Record Formats” section of this chapter.

C-22 Model 3321 Aerodynamic Particle Sizer Spectrometer

Unpolled Record Form a ts

The following are examples of unpolled record formats. These records are
comma delimited.

Accumulator (TOF) Data Record (A)

CS,A,SNX,tindex,ffff,stime,dtime,evt1,evt3,evt4,total,a1,a2,a3,... an
(the record is not available in Averaging or Correlated modes)
CS = Checksum
A = Accumulator (TOF) Data Record
S = S for Summed Mode
C Correlated mode
N = N for normal operation
A if in autocal mode
D if in autocal and autocal was “done” at the beginning of this

sample
X = X for spare position
tindex = time index 0 to sample time value - 1
(note if enabled for unpolled operation the
record is always reported when tindex = 0)
ffff = 4 digit hex value for status flags (see RF command)
stime = sample time not corrected for dead time
dtime = dead time (ms for 3321, µs for 3320)
evt1 = number of single hump events
evt3 = number of 3+ hump events
evt4 = number of timer overflow events
total = total (2-hump) particles measured (sum of reported channels,

evt 2)
a1... an = particle counts in each accumulator TOF bin (no zeros and

n=1023)

Using Serial Data Commands C-23

SS Accumulator Data Record (B)

CS,B,SNX,tindex,ffff,stime,dtime,ev1,evt3,evt4,total,b1,b2,b3,... bn
(the record is not available in Averaging or Correlated modes)
CS = Checksum
B = Side Scatter Accumulator Data Record
S = S for Summed Mode
C Correlated mode
N = N for normal operation
A if in autocal mode
D if in autocal and autocal was “done” at the beginning of

this sample
X = X for spare position
tindex = time index 0 to sample time value - 1
(note if enabled for unpolled operation the
record is always reported when tindex = 0)
ffff = 4 digit hex value for status flags (see RF command)
stime = sample time not corrected for dead time
dtime = dead time
evt1 = number of single hump events
evt3 = number of 3+ hump events
evt4 = number of timer overflow events
total = total (2-hump) particles measured (sum of reported

channels, evt 2)
b1... bn = particle counts in each pulse height accumulator bin (n=64)

C-24 Model 3321 Aerodynamic Particle Sizer Spectrometer

Correlated (Paired) Data Record (C)

The C record is a multi-record report with a header (C0) followed by n more
records (C1...Cn)
CS,C,0,PNX,tindex,ffff,stime,dtime,evt1,evt3,evt4,total,n,m (the C records
only available in Correlated mode)
CS = Checksum
C = Correlated (Paired) Data Record
0 = 0 indicates header record for C data report
P = C for Correlated Mode
N = N for normal operation
A if in autocal mode
D if in autocal and autocal was “done” at the beginning of this

sample
X = X for spare position
tindex = time index 0 to sample time value - 1
(note if enabled for unpolled operation the
record is always reported when tindex = 0)
ffff = 4 digit hex value for status flags (see RF command)
stime = sample time not corrected for dead time
dtime = dead time (ms for 3321, µs for 3320)
evt1 = number of single hump events
evt3 = number of 3+ hump events
evt4 = number of timer overflow events
total = total (2-hump) particles measured (sum of reported channels,

evt 2)
n = number of C (TOF) records to follow this record
m = number of SS fields per record (set by SCR command)

CS,C,n,c1,c2,c3,... cm
CS = Checksum
C = correlated (paired) data record
n = C1 to Cn records of correlated data where n is the number of

the aerodynamic dia. chan.
(each record contains data for one aerodynamic particle size

channel)
c1... cm = particle counts in each pulse height accumulator bin (no

zeros)

Using Serial Data Commands C-25

Aerodynamic (TOF) Data Record (D)

CS,D,ANX,tindex,ffff,stime,dtime,evt1,evt3,evt4,total,d1,d2,d3,... dn
CS = Checksum
D = Aerodynamic Data Record
A = A for Averaging Mode
S for Summed Mode
C for Correlated Mode
N = N for normal operation
A if in autocal mode
D if in autocal and autocal was “done” at the beginning of this

sample
X = X for spare position
tindex = time index 0 to sample time value - 1
(note if enabled for unpolled operation the
record is always reported when tindex = 0)
ffff = 4 digit hex value for status flags (see RF command)
stime = sample time not corrected for dead time
dtime = dead time (ms for 3321, µs for 3320)
evt1 = number of single hump events
evt3 = number of 3+ hump events
evt4 = number of timer overflow events
total = total (2-hump) particles measured (sum of reported

channels, evt 2)
d1... dn = particle counts in calibrated diameter channels (n determined

by SCA data usually 52)

SS Data Record (S)

CS,S,ANX,tindex,ffff,stime,dtime,evt1,evt3,evt4,total,h1,h2,h3,... hn
CS = Checksum
S = Side Scatter Data Record
A = A for Averaging Mode
S for Summed Mode
C for Correlated Mode
N = N for normal operation
A if in autocal mode
D if in autocal and autocal was “done” at the beginning of

this sample
X = X for spare position
tindex = time index 0 to sample time value - 1
(note if enabled for unpolled operation the
record is always reported when tindex = 0)
ffff = 4 digit hex value for status flags (see RF command)
stime = sample time not corrected for dead time
dtime = dead time (ms for 3321, µs for 3320)
evt1 = number of single hump events
evt3 = number of 3+ hump events
evt4 = number of timer overflow events
total = total (2-hump) particles measured (sum of reported

channels, evt 2)
h1... hn = particle counts in SS channels (n set by SCR command)

C-26 Model 3321 Aerodynamic Particle Sizer Spectrometer

Auxiliary Data Record (Y)

CS,Y,bpress,tflow,sflow,a0,a1,d0,d1,d2,lpower,lcur,spumpv,tpumpv,itemp,
btemp,dtemp,Vop
CS = Checksum
Y = Auxiliary Data Record
bpress = barometric inlet pressure (average over sample time)
tflow = total flow (average over sample time)
sflow = sheath flow (average over sample time)
a0 = Analog input voltage 0(I/O connector pin 7 ref to pin 15

(average over sample time)

a1 = Analog input voltage 1(I/O connector pin 8 ref to pin 15

(average over sample time)

d0 = Digital input level of I/O connector pin 1 ref to GND (pins 9,

10)

d1 = Digital input level of I/O connector pin 2 ref to GND (pins 9,

10)

d2 = Digital input level of I/O connector pin 3 ref to GND (pins 9,

10)
lpower = laser power (% of maximum power)
lcur = laser current (ma)
spumpv = sheath pump voltage
tpumpv = total pump voltage
itemp = inlet temperature in degrees C (ex. 25.5)
btemp = internal box temperature in degrees C (ex. 31.5)
dtemp = detector temperature for APD and optics in degrees C (ex:

25.5)
Vop = APD operating voltage in volts

How to Input Commands a n d Troubleshoot the Results

Use the following information as a guide to inputting software commands

and for troubleshooting possible problems.

Input Guidelines

 Input all alpha characters as capital letters (SMZ, not smz).
 Separate parameters with commas, not spaces.
 If you are in a command string, use the <Backspace> key to back up

and make changes. Do not use <arrow> keys.

 At the end of a command string, press <Enter> to complete the string.

Using Serial Data Commands C-27

Symptom

Possible Problem

Refer to

"Error" message
after pressing
<Enter>

An invalid command; command does not
exist.

An invalid parameter, which includes too
many parameters or a parameter that is out­of-range.

Incorrect syntax

Figure C-2 in this section.

The command showing the range and
an example.

"Input Guidelines" in this section.

No response after
pressing <Enter>

In unpolled mode

Use the U0 command to disable
unpolled mode. Enter U1 if an "OK" is
returned.

Serial cable

Check the cable and the cable
connection. See Chapter 2, "Unpacking

and System Setup."

Incorrect COM port

Check the COM port specified in the
software.

Incorrect baud rate

Software must be set at 9600, 19200, or
38400 baud to match instrument setting.
Also check computer hardware.

RS232 chip on the Model 3321

Contact TSI. Refer to "Contacting

Customer Service."

Model 3321 is locked up

Remove power from the Model 3321,
then apply power to the instrument. If
the problem continues, contact TSI.

Troubleshooting Input

Use Table C-4 as a troubleshooting guide.

Table C-4
Troubleshooting Serial Commands

C-28 Model 3321 Aerodynamic Particle Sizer Spectrometer

Measurement technique .......................

The time-of-flight of individual particles is measured in an accelerating flow field.
Processing electronics measure the time-of-flight of the particle using a single
high-speed timing processor. Phantom particle rejection is achieved through the
use of a patent pending double crested optical system. The particle size binning
is based on an internally stored calibration curve.

Particle Type ........................................

Airborne solids and non-volatile liquids.

Particle Size Range ..............................

0.5 to 20 m aerodynamic size, 0.3 to 20 m optical size (PSL equivalent)

Maximum Particle Concentration ..........

1000 pt/cm3 at 0.5 µm with less than 5% coincidence. 1,000 pt/cm3 at 10.0 µm
with less than 10% coincidence. Usable data up to 10,000 pt/cm3.

Display Resolution ................................

32 channels per decade of particle size (logarithmic). This results in 52 channels
total. 1,024 bins of raw time-of-flight data (4 nsec per bin) in uncorrelated mode.

Resolution ............................................

0.02 m at 1.0 m diameter. 0.03 m at 10 m diameter.

Sampling Time .....................................

Programmable from 1 second to 18 hours.

Flow Rates ...........................................

Total flow: 5.0 L/min ±1%, Sheath flow 4.0 L/min ±1%, Aerosol Sample 1.0 L/min
±10% (feedback controlled).

Atmospheric Pressure Correction .........

Automatic correction between 400 and 1,030 mbar (full correction between 700
and 1,030 mbar).

Concentration Accuracy .......................

±10% of reading plus variation from counting statistics.

Operating Temperature ........................

10 to 40°C (50 to 104°F).

Operating Humidity ...............................

10 to 90% RH non-condensing.

Laser Source ........................................

30 mW, 655 nm laser diode.

Detector ................................................

Avalanche photodetector (APD).

Front Panel Display ..............................

320 by 240 pixels.

Power ...................................................

100 to 240 VAC, 50–60 Hz, 100 W, single phase or 24 VDC.

Communications ...................................

RS232 (9-pin) port, 7 bits, even parity, 9600:19200:38400 baud.

Outputs .................................................

Digital I/O: 15-pin port (3 input, 3 output). Analog and digital pulse: BNC.
Configurable analog: BNC.

Dimensions (HWD) ...............................

18 cm  30 cm  38 cm (7 in.  12 in. 15 in.)

A P P E N D I X D

Model 3321
Specifications

The following specifications—which are subject to change—list the most
important features of the Model 3321.

Table D-1

Specifications of the Model 3321 Aerodynamic Particle Sizer® (APS™) Spectrometer

D-1

Weight ..................................................

10 kg (22 lb.).

Fuse (not replaceable by user)

(internal to power supply -- not

accessible by operator) .........................

~T 6.3A SB/250V

TSI and TSI logo are registered trademarks of TSI Incorporated.

D-2 Model 3321 Aerodynamic Particle Sizer Spectrometer

Index

A

AC power connector, 3-5
accumulator (TOF) data record

(A), C-23

action commands, C-4, C-13

beep, C-13
clear buffer and sample

time, C-14
dump, C-14
fill accumulators, C-14
go, C-14
halt, C-14
laser enable/disable, C-15
perform APD autocal, C-13
quick concentration report, C-15
sampling, C-15

aerodynamic (TOF) data record

(D), C-26

Aerodynamic Particle Sizer

Spectrometer, 1-2

aerosol flow, 5-2
applications, 1-2
back panel, 3-5
BNC connector, 2-5
calibration, A-9
Class I laser, v
collecting data, 4-4
connecting computer, 2-4
description, 1-1, 3-1
front panel, 3-1, 3-2
history, 1-4
I/O port, 2-5
indicators, 3-4
inlet nozzle, 3-4
inputting commands, C-27
internal components, 3-8
internal diagram, 3-9
labels, v
location of warning labels, vi
maintenance, A-1
menu layout, 3-3
mounting sensor, 2-2
operation, 1-3, 4-1
optics cross section, 5-4
overview, 1-1
packing list, 2-1
power connection, 2-4
safety, v
sample setup, 4-1
serial data commands, C-1
serial port connector, 2-4
setting up, 2-1
specifications, D-1
theory of operation, 5-1
troubleshooting, B-1
unpacking, 2-1

Aerodynamic Particle Sizer

Spectrometer, (continued)

ventilation requirements, 2-3

analog module, 5-6

differential circuit, 5-6
gate circuit, 5-6

side-scatter circuit, 5-7
Analog Out, 3-8
analog PC board, 3-8
APD module, 5-5
applications, 1-2
APS. (see Aerodynamic Particle Sizer

Spectrometer)
APS menu screen, 4-2
auxiliary data record (Y), C-27

B

back panel, 3-5
baud rate, C-2
beep, C-13
begin unpolled operation, C-20
BNC connector, 2-5
BNC connectors, 3-8

Analog Out, 3-8
Pulse Out, 3-8
Timeof Flight, 3-8

C

calibration, A-9
change graphic display, 3-3
Class 1 laser, v
cleaning inner nozzle, A-2
cleaning outer nozzle, A-3
clear accumulator, 3-3
clear buffer and sample time, C-14
collecting data, 4-4
commands, C-3

inputting, C-27
computer, connecting, 2-4
connecting computer, 2-4
connecting power, 2-4
connectors

AC power, 3-5

BNC, 3-8
contacting TSI, 6-1
correlated (paired) data record

(C), C-25
correlated mode, 5-9
customer service, 6-1

D

data collection, 4-4
DC power input, 3-6
description of APS, 3-1
detector PC board, 3-8
diable all records, C-20

differential circuit, 5-6
digital, 5-8
digital module, 5-7

correlated mode, 5-9
event 1, 5-7
event 3, 5-8
event 4, 5-8

uncorrelated mode, 5-9
digital PC board, 3-8
double-crested signal

example, 5-5
dump, C-14

E

enable all records, C-20
EPROM

location of chips, A-8

replacing, A-7

F

fill accumulators, C-14
filter

replacing, A-6
filters, 3-8
FLOW LED, 3-4
flow path sample, 5-1
front panel, 3-1

G

gate circuit, 5-6
generate accumulator report record

(report record A), C-21

generate aerodynamic data report

record (report record D), C-22

generate auxiliary report record

(report record Y), C-22

generate correlated (paired) report

record (report record C), C-21

generate side scatter accumulator

report record (report record
B), C-21

generate side scatter data report

record (report record S), C-22
go, C-14
graphic display

changing, 3-3

H

halt, C-14
help, 6-1
HI CONC LED, 3-4
history, 1-4

I–J–K

I/O port, 2-5, 3-7

pin designations, 3-7

Index Index-1

indicators, 3-4
inlet nozzle, 3-4
internal components, 3-8
internal diagram of APS, 3-9

L

labels, v
laser enable/disable, C-15
LASER LED, 3-4
laser PC board, 3-8
LCD display, 3-1
LED

Flow, 3-4
Hi Conc, 3-4
Laser, 3-4
Particle, 3-4
Power, 3-4

location of warning labels, vi

M–N

maintenance, A-1

calibration, A-9
cleaning inner nozzle, A-2
cleaning outer nozzle, A-3
replacing EPROM, A-7
replacing filters, A-6

schedule, A-1
manual history, ii
menu items

description, 4-3
menu layout, 3-3
mounting sensor, 2-2

O

operation, 1-3, 4-1
optics, 3-8
optics path, 5-3

P

packing instructions, 6-2
packing list, 2-1
parity, C-2
particle coincidence, 5-9
PARTICLE LED, 3-4
perform APD autocal, C-13
pin connectors, C-1
power connection, 2-4
power input, DC, 3-6
POWER LED, 3-4
Power PC board, 3-8
power supply, 3-8
product registration, ii
Pulse Out, 3-8
pump exhaust, 3-6

Q

quick concentration report, C-15

R

read (polled) commands, C-4
read accumulated on time, C-17

read accumulator, C-16
read aerosol sample flow, C-18
read commands (polled)

read accumulated on time, C-17
read accumulator, C-16
read aerosol sample flow, C-18
read firmware version, C-20
read flags, C-16
read inlet pressure, C-18
read input from pins 1, 2, 3 and 7,

8 of the I/O connector, C-17
read laser power, C-17
read record, C-19
read sheath Delta P, C-18
read sheath flow, C-18
read temperature in box, C-19
read temperature of

detector, C-19
read temperature of inlet, C-19
read total Delta P, C-18
read total flow, C-18

read firmware version, C-20
read flags, C-16
read inlet pressure, C-18
read input from pins 1, 2, 3 and 7, 8 of

the I/O connector, C-17
read laser power, C-17
read record, C-19
read sheath Delta P, C-18
read sheath flow, C-18
read temperature in box, C-19
read temperature of detector, C-19
read temperature of inlet, C-19
read total Delta P, C-18
read total flow, C-18
related product literature, xiii
replacing EPROM, A-7
replacing filters, A-6
restart sample, 3-3
returning for service, 6-2

S

safety, v
sample flow path, 5-1
sample setup, 4-1
sampling, C-15
sensor, mounting, 2-2
serial data commands, C-1

action commands, C-4, (see also

action commands)
baud rate, C-2
commands, C-3
parity, C-2
pin connectors, C-1
read (polled) commands, C-4
read commands (polled). (see

also read commands (polled)
set commands, C-4, (see also set

commands)
stop bits and flow control, C-2
unpolled commands, C-4, (see

also unpolled commands):

serial data commands (continued)

unpolled record formats. (see

also unpolled record formats)
serial port, 3-7
serial port connector, 2-4
service

returning, 6-2
set analog output voltage, C-13
set baud rate, C-5
set calibration environment, C-7
set calibration for aerodynamic

diameters, C-5
set calibration label string, C-6
set calibration resolution, C-7
set commands, C-4, C-5

set analog output voltage, C-13
set baud rate, C-5
set calibration environment, C-7
set calibration for aerodynamic

diameters, C-5
set calibration label string, C-6
set calibration resoluation, C-7
set digital output, C-7
set front panel enable, C-8
set hi conc threshold, C-9
set laser power, C-9
set mode and sample time, C-11
set mode for analog output, C-10
set mode for automatic calibration

of APD, C-11
set pumps, C-12
set time for unpolled report, C-12

set digital output, C-7
set front panel enable, C-8
set hi conc threshold, C-9
set laser power, C-9
set mode and sample time, C-11
set mode for analog output, C-10
set mode for automatic calibration of

APD, C-11
set pumps, C-12
set time for unpolled report, C-12
setting up, 2-1
sheath flow pump, 3-8
side scatter circuit, 5-7
signal processing path, 5-5
specifications, D-1
SS accumulator data record (B), C-24
SS data record (S), C-26
stop bits and flow control, C-2

T

technical contacts, 6-1
theory of operation, 5-1
Time of Flight, 3-8
total flow pump, 3-8
trademarks, iv
troubleshooting, B-1

symptoms and

recommendations, B-1

turn display on, 3-3

Index-2 Model 3321 Aerodynamic Particle Sizer Spectrometer

U

uncorrelated mode, 5-9
unpacking, 2-1
unpolled commands, C-4, C-20

begin unpolled operation, C-20
disable all records, C-20
enable all records, C-20
generate accumulator report

record (report record A), C-21

generate aerodynamic data

report record (report record
D), C-22

generate auxiliary report record

(report record Y), C-22

generate correlated (paired)

report record (report record
C), C-21

generate side scatter

accumulator report record
(report record B), C-21

generate side scatter data report

record (report record S), C-22

unpolled record formats, C-23

accumulator (TOF) data record

(A), C-23

aerodynamic (TOF) data record

(D), C-26
auxiliary data record (Y), C-27
correlated (paired) data record

(C), C-25
SS accumulator data record

(B), C-24
SS data record (S), C-26

V

ventilation requirements, 2-3
view information, 3-3

W–X–Y–Z

warning, v
warning labels

location, vi

warranty, iii

Index Index-3

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