AMI 1700 Manual

Revision 2; 3 August 2016
American Magnetics, Inc.
P.O. Box 2509, 112 Flint Road, Oak Ridge, TN 37831-2509, Tel: [phone], Fax: [phone]
MODEL 1700
LIQUID LEVEL INSTRUMENT
(LIQUID NITROGEN VERSION)
INSTALLATION, OPERATION, AND
MAINTENANCE INSTRUCTIONS
EXCELLENCE IN MAGNETICS AND CRYOGENICS
1CoverPage

Revision 2; 3 August 2016

Rev. 2 i
Table of Contents
Cover Page...................................................................................................... i
Table of Contents ........................................................................................... i
List of Figures................................................................................................ v
List of Tables ................................................................................................ ix
Foreword ....................................................................................................... xi
Purpose and Scope ............................................................................................. xi
Contents of this Manual ..................................................................................... xi
General Precautions ..........................................................................................xii
Cryogen Safety Summary ................................................................................xiii
Safety Legend .................................................................................................. xiv
Equipment Warnings......................................................................................... xv
Instrument Configuration.................................................................................. xv
Introduction ................................................................................................... 1
1.1 Model 1700 Instrument....................................................................................... 1
1.1.1 Cryogenic (Capacitance-Based) Liquid Level Sensors ......................... 1
1.1.2 Digitally-Controlled............................................................................... 3
1.1.3 System Flexibility .................................................................................. 3
1.1.4 Display ................................................................................................... 3
1.1.5 Intuitive Human-Interface Design ......................................................... 4
1.1.6 Measurement Flexibility ........................................................................ 4
1.1.7 Real Time Clock .................................................................................... 4
1.1.8 Valve Control Output............................................................................. 4
1.1.9 Analog Outputs ...................................................................................... 4
1.1.10 Signal Relays.......................................................................................... 4
1.1.11 Connectivity........................................................................................... 4
1.2 Model 1700 Front Panel Layout ......................................................................... 6
1.3 Model 1700 Rear Panel Layout .......................................................................... 6
1.4 Model 1700 Specifications @ 25°C.................................................................... 7
Installation ................................................................................................... 11
2.1 Unpacking and Inspecting the Instrument ........................................................ 11
2.2 Mounting the Model 1700 Instrument .............................................................. 11
2.3 Installing Capacitance-Based Liquid Level Sensors......................................... 11
1 Table of
Contents

ii Rev. 2
Table of Contents
2.4 Connecting the Sensor to the Instrument .......................................................... 12
2.4.1 Connecting a Capacitance Sensor ........................................................13
2.5 Setting Up an Autofill System ......................................................................... 14
2.5.1 Autofill System Description................................................................. 14
2.5.2 Autofill System Setup .......................................................................... 16
2.6 Power Requirements ......................................................................................... 17
Operation ......................................................................................................19
3.1 Energizing the Model 1700 Instrument............................................................. 19
3.2 Screen Navigation ............................................................................................. 19
3.2.1 Home Screen Footer............................................................................. 19
3.3 Navigating the Instrument Menus..................................................................... 20
3.3.1 Menu Overview.................................................................................... 20
3.3.2 Editing a Field...................................................................................... 24
3.3.3 Menu Navigation.................................................................................. 26
3.4 Capacitance (Liquid Nitrogen) Level................................................................26
3.4.1 Configure the instrument to display nitrogen level..............................26
3.4.2 Other Liquid Helium Functions ........................................................... 27
3.4.3 Other Liquid Helium Functions ........................................................... 27
3.5 Alarms and Relays ............................................................................................ 27
3.5.1 Overview .............................................................................................. 27
3.5.1.1 Level-Based Alarms.................................................................. 27
3.5.1.2 Time-Based Fill Alarm ............................................................. 28
3.5.1.3 Multiple alarms ......................................................................... 28
3.5.2 Configuring Alarm Setpoints ............................................................... 29
3.5.3 Acknowledging an Alarm .................................................................... 29
3.5.4 Muting an Alarm.................................................................................. 30
3.5.5 Resetting the Autofill Timeout Alarm .................................................30
3.6 Configure the Autofill Function........................................................................ 31
3.6.1 Autofill overview ................................................................................. 31
3.6.2 Setting the autofill parameters ............................................................. 31
3.6.3 Enable the Autofill function................................................................. 31
3.7 Select the appropriate units on the display........................................................32
3.8 Analog output signals........................................................................................ 32
3.8.1 Connecting to the Aux Connector........................................................32
3.8.2 Configuring the Analog Outputs.......................................................... 33
3.9 Ethernet Connectivity........................................................................................ 33
3.9.1 IP Addressing Scheme ......................................................................... 33
3.10 Abnormal Operation.......................................................................................... 34

Rev. 2 iii
Table of Contents
3.10.1 Capacitance Sensor Contamination ..................................................... 34
3.10.2 Resetting the Instrument to Factory Defaults ...................................... 35
3.11 Shutting the Instrument Down .......................................................................... 36
Calibration.................................................................................................... 37
4.1 Setting the System Date and Time.................................................................... 37
4.2 Capacitance-based Level Calibration................................................................ 38
4.2.1 Understanding the Sensor Active Length ............................................ 38
4.2.2 Relationship between Calibration and Sensor Length ......................... 40
4.2.3 Variations in the Dielectric with Changing Density ............................ 40
4.2.4 Capacitance-based Sensor Calibration Methods.................................. 41
4.2.4.1 Selection of Capacitance Sensor Calibration Methods............. 42
4.2.5 Pre-Calibration Procedure.................................................................... 44
4.2.5.1 Enter Capacitance Sensor Information ..................................... 44
4.2.5.2 Performing Loss of Sensor Calibration .................................... 46
4.2.6 Performing an Open Dewar Calibration .............................................. 48
4.2.7 Approximate Calibration...................................................................... 49
4.2.8 Closed Dewar Calibration.................................................................... 53
4.2.8.1 Presetting the maximum and minimum calibration points ....... 53
4.2.8.2 Completing the closed dewar calibration procedure................. 55
Remote Interface Reference....................................................................... 61
5.1 SCPI Command Summary ................................................................................ 61
5.2 SCPI Ethernet Communication ......................................................................... 61
5.3 SCPI Serial (RS-232) Communication ............................................................. 62
5.3.1 Serial port connector and cabling......................................................... 62
5.4 Command/return termination characters........................................................... 62
5.5 Command Set Reference................................................................................... 63
5.5.1 Commands for determining the instrument configuration................... 63
5.5.2 Commands for setting the units of measurement................................. 68
5.5.3 Commands for configuring setpoints................................................... 69
5.5.4 Commands for setting the channel identifiers...................................... 72
5.5.5 Commands for making liquid level measurements.............................. 73
5.5.6 Commands for calibrating level sensors .............................................. 74
5.5.7 System Commands............................................................................... 75
5.6 Error Codes ....................................................................................................... 76
Service and Repair ...................................................................................... 79
6.1 Cleaning ............................................................................................................ 79
6.2 User Replaceable Parts...................................................................................... 79

iv Rev. 2
Table of Contents
6.3 Battery Replacement ......................................................................................... 80
6.3.1 Tools Required ..................................................................................... 80
6.3.2 Procedure.............................................................................................. 80
6.4 Fuse Replacement ............................................................................................. 81
6.4.1 Tools Required ..................................................................................... 81
6.4.2 Procedure.............................................................................................. 81
Appendix.......................................................................................................83
A.1 Connector Wiring.............................................................................................. 83
A.1.1 Serial (RS-232) Connector ................................................................... 83
A.1.2 Ethernet Connector............................................................................... 84
A.1.3 Aux I/O Connector............................................................................... 85
A.2 Troubleshooting ................................................................................................ 86
A.3 Firmware Licenses ............................................................................................ 86
Glossary........................................................................................................95
Abbreviations and Acronyms Used in This Manual ......................................... 95
Index..............................................................................................................97

Rev 2 v
List of Figures
Figure 1-1 Model 1700 Instrument using internal oscillator/transmitter 2
Figure 1-2 Model 1700 Instrument using external oscillator/transmitter3
Figure 1-3 Model 1700 Nitrogen Instrument Via Web Browser............... 5
Figure 1-4 Model 1700 Front View; Dual Channel Instrument Shown ... 6
Figure 2-1 Model 1700 Instrument in an Autofill configuration ............ 15
Figure 2-1 Typical Autofill Setup ............................................................. 15
Figure 2-2 Loss Of Nitrogen Level Sensor ............................................... 17
Figure 3-1 LN2 Home Screen ................................................................... 19
Figure 3-2 Home Screen Footer ................................................................ 20
Figure 3-3 MENU button on HOME screen............................................. 20
Figure 3-4 MENU Selection Screen.......................................................... 20
Figure 3-5 HOME button on MENU screen............................................. 20
Figure 3-6 BACK button ........................................................................... 20
Figure 3-7 Field Editing Footer ................................................................ 24
Figure 3-8 Model 1700 Menu Structure ................................................... 26
Figure 3-9 INTERNAL Oscillator Indicated ............................................ 27
Figure 3-10 Nitrogen Level Displayed on Home Screen ........................... 27
Figure 3-11 Fill Timeout Alarm Screen ..................................................... 28
Figure 3-12 Output Configuration Screen, Page 1 .................................... 29
Figure 3-13 Relay Source Configuration .................................................... 29
Figure 3-14 Relay Setpoints........................................................................ 29
Figure 3-15 Alarm Condition Above or Below Setpoints........................... 29
Figure 3-16 Alarm Annunciator ................................................................. 30
Figure 3-17 LO LEVEL Alarm Condition Footer Displays ....................... 30
Figure 3-18 Muted Alarm Condition .......................................................... 30
Figure 3-19 Autofill Level Control Selection.............................................. 31
Figure 3-20 Autofill Level Start Setting .................................................... 31
Figure 3-21 Autofill Timeout Setting ......................................................... 31
Figure 3-22 LN2 Home Screen ................................................................... 32
Figure 3-23 Analog Outputs Source Selection ........................................... 33
Figure 3-24 Network Selection ................................................................... 33
Figure 3-25 Editing Network Selection...................................................... 33
Figure 3-26 Editing Network Settings ....................................................... 33
Figure 3-27 Saving Network Settings ........................................................ 34
Figure 3-28 System Menu, Page 2.............................................................. 35
Figure 3-29 Resetting Instrument to Factory Defaults............................. 35
Figure 3-30 Invoking Instrument Shut Down ........................................... 36
Figure 3-31 Confirming Instrument Shut Down ....................................... 36
Figure 4-1 Menu Selection From Home Screen ....................................... 37
Figure 4-2 Menu Selection Screen............................................................ 37
Figure 4-3 System Menu, Page 1.............................................................. 37
Figure 4-4 System Menu, Page 2.............................................................. 38
1Listof
Figures

vi Rev 2
List of Figures
Figure 4-5 Typical Capacitance-based Liquid Level Sensor....................39
Figure 4-6 Dielectric vs. pressure for nitrogen under saturated conditions.
41
Figure 4-7 Calibration method selection diagram....................................43
Figure 4-8 MENU Selection Button ..........................................................44
Figure 4-9 SENSORS Selection Button ....................................................44
Figure 4-10 NITROGEN OSCILLATOR Selection.....................................44
Figure 4-11 CALIBRATE NITROGEN Selection Button...........................45
Figure 4-12 SENSOR ACTIVE LENGTH field ..........................................45
Figure 4-13 Footer BACK Button Selection................................................45
Figure 4-14 SYSTEM Menu Selection ........................................................45
Figure 4-15 PERFORM MAX CAL. Selection Button ................................46
Figure 4-16 Home Selection Button ............................................................46
Figure 4-17 MENU Selection Button ..........................................................46
Figure 4-18 SENSORS Selection Button ....................................................47
Figure 4-19 CALIBRATE NITROGEN Selection Button...........................47
Figure 4-20 NO SENSOR CAL button........................................................47
Figure 4-21 MENU Selection Button ..........................................................48
Figure 4-22 SENSORS Selection Button ....................................................48
Figure 4-23 CALIBRATE NITROGEN Selection Button...........................48
Figure 4-24 PERFORM MAX CAL. Selection Button ................................48
Figure 4-25 Updated MAX CAL Frequency................................................49
Figure 4-26 PERFORM MIN CAL. Selection Button.................................49
Figure 4-27 MENU Selection Button ..........................................................50
Figure 4-28 SENSORS Selection Button ....................................................50
Figure 4-29 CALIBRATE NITROGEN Selection Button...........................50
Figure 4-30 PERFORM MAX CAL. Selection Button ................................50
Figure 4-31 Updated MAX CAL Frequency................................................51
Figure 4-32 PERFORM MIN CAL. Selection Button.................................51
Figure 4-33 APPROX. CAL. VALUE field ..................................................52
Figure 4-34 MAX CAL values edited...........................................................52
Figure 4-35 MENU Selection Button ..........................................................54
Figure 4-36 SENSORS Selection Button ....................................................54
Figure 4-37 CALIBRATE NITROGEN Selection Button...........................54
Figure 4-38 PERFORM MIN CAL. Selection Button.................................54
Figure 4-39 PERFORM MAX CAL. Selection Button ................................55
Figure 4-40 PERFORM MAX CAL. Selection Button ................................55
Figure 4-41 PERFORM MAX CAL. Selection Button ................................56
Figure 4-42 PERFORM MAX CAL. Selection Button ................................57
Figure 4-43 Updated MAX CAL Frequency................................................58
Figure A-1 Serial (RS-232) Pin Out ...........................................................83
Figure A-2 Ethernet Connector Socket Pin out.........................................84

Rev 2 vii
List of Figures
Figure A-3 Aux I/O Connector................................................................... 85

viii Rev 2
List of Figures

Rev 2 ix
List of Tables
Table 1-1 Model 1700 Rear Panel Description ......................................... 6
Table 2-1 Standard Autofill Setup Description...................................... 15
Table 3-1 Model 1700 Instrument Home Screen Footer........................ 20
Table 3-2 Model 1700 Nitrogen Instrument Menu Structure ............... 21
Table 3-3 Model 1700 Instrument Footer during editing a field........... 25
Table 3-4 Autofill Settings ...................................................................... 32
Table A-1 Serial (RS-232) Pin Definitions .............................................. 83
Table A-2 Ethernet RJ-45 Connector Pin Definitions............................ 84
Table A-3 Aux I/O Pin Definitions........................................................... 85
1Listof
Tables

xRev 2
List of Tables

Rev. 2 xi
Foreword
Purpose and Scope
This manual contains the operation and maintenance instructions for the
American Magnetics, Inc. Model 1700 Liquid Level Control Instrument
and outlines applications for various system configurations. Since it is not
possible to cover all equipment combinations for all magnet systems, only
the most common configurations are discussed. The user is encouraged to
contact an authorized AMI Technical Support Representative for
information regarding specific configurations not explicitly covered in this
manual. This manual refers to the instrument as configured for liquid
nitrogen operation.
Contents of this Manual
Introduction describes the functions, specifications, and characteristics
of the Model 1700 Instrument. It provides illustrations of the front and
rear panel layouts as well as documenting the performance specifications.
Additional information is provided in the form of system block diagrams.
Installation describes how the Model 1700 Instrument is unpacked and
installed in conjunction with ancillary equipment in typical systems.
Block-level diagrams document the interconnects for various system
configurations.
Operation describes how the Model 1700 Instrument is used to monitor
and automatically control liquid nitrogen levels.
Calibration describes the various calibration techniques for liquid
nitrogen level sensors.
Remote Interface Reference documents all remote commands and
queries available through the Model 1700 Instrument RS-232 and
Ethernet interfaces. A quick-reference summary of commands is provided
as well as a detailed description of each.
The Appendix and Glossary sections support the information in the
sections listed above. See the Appendix section when referenced from other
sections. See the Glossary for any words or acronyms presented in the
above sections, requiring a more complete understanding.

xii Rev. 2
Foreword
General Precautions
General Precautions
Cryogen Safety
The two most common cryogenic liquids used in superconducting magnet
systems are nitrogen and helium. Both of these cryogens are extremely
cold at atmospheric pressure (321°F and 452°F, respectively). The
following paragraphs outline safe handling precautions for these liquids.
Personnel handling cryogenic liquids should be thoroughly instructed and
trained as to the nature of the liquids. Training is essential to minimize
accidental spilling. Due to the low temperature of these materials, a
cryogen spilled on many objects or surfaces may damage the surface or
cause the object to shatter, often in an explosive manner.
Inert gases released into a confined or inadequately ventilated space can
displace sufficient oxygen to make the local atmosphere incapable of
sustaining life. Liquefied gases are potentially extreme suffocation
hazards since a small amount of liquid will vaporize and yield a very large
volume of oxygen-displacing gas. Always ensure the location where the
cryogen is used is well ventilated. Breathing air with insufficient oxygen
content may cause unconsciousness without warning. If a space is suspect,
purge the space completely with air and test before entry. If this is not
possible, wear a forced-air respirator and enter only with a co-worker
standing by wearing a forced-air respirator.
Cryogenic liquids, due to their extremely low temperatures, will also burn
the skin in a similar manner as would hot liquids. Never permit cryogenic
liquids to come into contact with the skin or allow liquid nitrogen to soak
clothing. Serious burns may result from careless handling. Never touch
uninsulated pipes or vessels containing cryogenic liquids. Flesh will stick
to extremely cold materials. Even nonmetallic materials are dangerous to
touch at low temperatures. The vapors expelled during the venting process
are sufficiently cold to burn flesh or freeze optic tissues. Insulated gloves
should be used to prevent frost-bite when operating valves on cryogenic
tanks. Be cautious with valves on cryogenic systems; the temperature
extremes they are typically subjected to cause seals to fail frequently.
In the event a person is burned by a cryogen or material cooled to
cryogenic temperatures, the following first aid treatment should be given
pending the arrival and treatment of a physician or other medical care
worker:
1. If any cryogenic liquid contacts the skin or eyes, immediately flush
the affected area gently with tepid water (102°F 105°F, 38.9°C 
40.5°C) and then apply cold compresses.

Rev. 2 xiii
Foreword
Safety Summary
2. Do not apply heat. Loosen any clothing that may restrict
circulation. Apply a sterile protective dressing to the affected area.
3. If the skin is blistered or there is any chance that the eyes have
been affected, get the patient immediately to a physician for
treatment.
Containers of cryogenic liquids are self pressurizing (as the liquid boils off,
vapor pressure increases). Hoses or lines used to transfer these liquids
should never be sealed at both ends (i.e. by closing valves at both ends).
When pouring cryogenic liquids from one container to another, the
receiving container should be cooled gradually to prevent damage by
thermal shock. The liquid should be poured slowly to avoid spattering due
to rapid boil off. The receiving vessel should be vented during the transfer.
Introduction of a substance at or near room temperature into a cryogenic
liquid should be done with great caution. There may be a violent gas boil-
off and a considerable amount of splashing as a result of this rapid boiling.
There is also a chance that the material may crack or catastrophically fail
due to forces caused by large differences in thermal contraction of different
regions of the material. Personnel engaged in this type of activity should
be instructed concerning this hazard and should always wear a full face
shield and protective clothing. If severe spraying or splashing could occur,
safety glasses or chemical goggles along with body length protective
aprons will provide additional protection.
The properties of many materials at extremely low temperatures may be
quite different from the properties that these same materials exhibit at
room temperatures. Exercise extreme care when handling materials cooled
to cryogenic temperatures until the properties of these materials under
these conditions are known.
Metals to be used for use in cryogenic equipment application must posses
sufficient physical properties at these low temperatures. Since ordinary
carbon steels, and to somewhat a lesser extent, alloy steels, lose much of
their ductility at low temperatures, they are considered unsatisfactory and
sometimes unsafe for these applications. The austinetic Ni-Cr alloys
exhibit good ductility at these low temperatures and the most widely used
is 18-8 stainless steel. Copper, Monel®, brass and aluminum are also
considered satisfactory materials for cryogenic service.
Cryogen Safety Summary
Cryogenic systems are complex systems with the potential to seriously
injure personnel or equipment if not operated according to procedures. The

xiv Rev. 2
Foreword
Safety Summary
use of safety mechanisms (pressure relief valves, rupture disks, etc.) in
cryogenic systems is usually necessary.
Recommended Safety Equipment
The use of proper safety equipment is necessary. Such equipment may
include, but not limited to, the following items:
•First Aid kit
•Fire extinguisher rated for class C fires
•Cryogenic gloves
•Face shield
•Signs to indicate that there are potentially dangerous cryogens in
use in the area.
Safety Legend
Instruction manual symbol: the product is marked with this
symbol when it is necessary for you to refer to the instruction
manual in order to protect against damage to the product or
personal injury.
Hazardous voltage symbol.
Alternating Current (Refer to IEC 417, No. 5032).
Off (Supply) (Refer to IEC 417, No. 5008).
On (Supply) (Refer to IEC 417, No. 5007).
Warning
The Warning sign denotes a hazard. It calls attention to a procedure or
practice, which if not correctly adhered to, could result in personal injury.
Do not proceed beyond a Warning sign until the indicated conditions are
fully understood and met.
Caution
The Caution sign denotes a hazard. It calls attention to an operating
procedure or practice, which if not adhered to, could cause damage or
destruction of a part or all of the product. Do not proceed beyond a Caution
sign until the indicated conditions are fully understood and met.
O
I

Rev. 2 xv
Foreword
Safety Summary
Equipment Warnings
Before energizing the equipment, the earth ground of the power receptacle
must be verified to be at earth potential and able to carry the rated current
of the power circuit. Using extension cords should be avoided. However, if
an extension cord must be used, insure the ground conductor is intact and
the cord is capable of carrying the rated current without excessive voltage
drop.
In the event that the ground path becomes less than sufficient to carry the
rated current of the power circuit, the equipment should be disconnected
from power, labeled as unsafe, and removed from place of operation.
Do not operate this equipment in the presence of flammable gases. Doing
so could result in a life-threatening explosion.
Do not modify this equipment in any way. If component replacement is
required, return the equipment to AMI facilities as described in the
troubleshooting section of this manual.
If used in a manner not specified in this manual, the protection provided
by the design, manufacture and documentation of the Model 1700
Instrument may be impaired.
Other Manual Conventions
This manual refers to measuring liquid nitrogen (LN2) when referring to
capacitance-based level measurement since nitrogen is by far the most
common cryogenic fluid used by this sort of instrument. This instrument
can be used to measure most any cryogenic liquid.
Instrument Configuration
The Model 1700 Instrument is configured at time of purchase as a
capacitance-based (typically liquid nitrogen) level instrument/controller.
Every configuration may be further customized by the following options:
•Table top, single rack mounting, dual rack mounting.
•Line cord: North American, European Schuko, Australia/NZ, China,
UK, pigtailed ends.
The instrument part number, shown on the serialization label located on
the underside of the instrument, as well as in a field in the instrument
Menu, identifies the configuration according to the following key:
1700-A-B-C-D-E where

xvi Rev. 2
Foreword
Safety Summary
Aindicates the mounting method:
Tbl = tabletop
SR19L = single rack mounted, 19” wide rack standard, instrument
on left side
SR19R = single rack mounted, 19” wide rack standard, instrument
on right side
SR10L = single rack mounted, 10” wide rack standard, instrument
on left side
SR10R = single rack mounted, 10” wide rack standard, instrument
on right side
DRL = dual rack mount, 19” wide rack standard, instrument on left
side
DRR = dual rack mount, 19” wide rack standard, instrument on
right side
Bindicates the line cord shipped with the instrument:
N = North American
E = European, Schuko
A = Australian/New Zealand
C = Chinese
U = United Kingdom
P = India/pigtailed
Cindicates the capacitance-based level configuration:
CAP = capacitance-based (typically nitrogen)
N = not configured
The sensor active length and length units are appended to the
configuration code, ie ...CAP-10.4CM-...
Dindicates the helium level configuration:
N = not configured
Eis used to denote any instrument customization:
S = standard (no customization)
C = instrument modified.

Rev. 2 1
1 Introduction
1.1 Model 1700 Instrument
The AMI Model 1700 Liquid Level Instrument is a sophisticated
measurement and control instrument which provides monitoring liquid
helium and/or capacitance-based level sensors as inputs and provides for
automatic level control based on user set parameters.
At time of purchase, the Model 1700 will be configured as:
• A capacitance-based (typically liquid nitrogen)1level instrument/
controller.
1.1.1 Cryogenic (Capacitance-Based) Liquid Level Sensors
The Model 1700 Instrument will be used with a capacitance-based sensor
for all cryogenic liquids except for helium. Special insulated capacitance
sensors are required for liquids with electrical conductivity, i.e. water.
The Model 1700 Instrument must use an oscillator device to measure
cryogenic liquid levels. This instrument has an internal oscillator if the
distance between the sensor and the instrument is less than or equal to 15
feet (457 cm) so no external oscillator is necessary. If the distance between
the sensor and the instrument is greater than 15 feet, an external
oscillator/transmitter unit is necessary. The instrument will automatically
1. The instrument can be used to measure/control any cryogenic liquid but the most
common is nitrogen.

2Rev. 2
Introduction
configure itself to use the internal oscillator unless the external oscillator/
transmitter is connected to the BNC connector on the rear panel.
Figure 1-1. Model 1700 Instrument using internal oscillator/
transmitter
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