Ametek SEQUOIA Series Owner's manual

M447353-01 Rev A April 2023 www.programmablepower.com
Sequoia Series
AC/DC Power Source
SCPI Programming Manual
M447353-01
SCPI Programming Reference Manual
Sequoia Series AC/DC Power Source

2 Sequoia Series

Sequoia Series 3
About AMETEK
AMETEK Programmable Power, Inc., a unit of AMETEK Electronic Instruments Group (a division of
AMETEK, Inc), is a global leader in the design and manufacture of precision, programmable power
supplies for R&D, test and measurement, process control, power bus simulation and power
conditioning applications across diverse industrial segments. From bench-top supplies to rack-
mounted industrial power subsystems, AMETEK Programmable Power is the proud manufacturer of
Elgar, Sorensen, California Instruments brand power supplies and electronic loads.
AMETEK, Inc. is a leading global manufacturer of electronic instruments and electromechanical
devices with annualized sales of $4 billion. The company has over 15,000 colleagues working at more
than 150 manufacturing facilities and more than 100 sales and service centers in the United States
and around the world.
Trademarks
AMETEK is a registered trademark of AMETEK, Inc. California Instruments is a trademark owned by
AMETEK, Inc. Other trademarks, registered trademarks, and product names are the property of their
respective owners and are used herein for identification purposes only.
Notice of Copyright
Sequoia Series Programming Manual © 2023 AMETEK Programmable Power, Inc. All rights reserved.
Exclusion for Documentation
UNLESS SPECIFICALLY AGREED TO IN WRITING, AMETEK PROGRAMMABLE POWER, INC. (“AMETEK”):
(a) MAKES NO WARRANTY AS TO THE ACCURACY, SUFFICIENCY OR SUITABILITY OF ANY
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DOCUMENTATION.
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WHETHER SPECIAL, DIRECT, INDIRECT, CONSEQUENTIAL OR INCIDENTAL, WHICH MIGHT
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BE ENTIRELY AT THE USER’S RISK, AND
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Date and Revision
April 2023, Revision A
Part Number
M447353-01
Contact Information
Telephone: [phone] (toll free in North America)
858 450 0085 (direct)
Fax: [phone]
Email: [e-mail]
[e-mail]
Web: www.programmablepower.com

4 Sequoia Series
Important Safety Instructions
Before applying power to the system, verify that your product is configured properly for your
application.
WARNING!
Hazardous voltages may be present when covers are removed. Qualified
personnel must use extreme caution when servicing this equipment. Circuit
boards, test points, and output voltages also may be floating at a high voltage
relative to chassis ground.
WARNING!
The equipment used contains ESD sensitive parts. When installing equipment,
follow ESD Safety Procedures. Electrostatic discharges might cause damage to
the equipment.
Only qualified personnel who deal with attendant hazards in power supplies, are allowed to perform
installation and servicing.
Ensure that the AC power line ground is connected properly to the Power Rack input connector or
chassis. Similarly, other power ground lines including those to application and maintenance equipment
must be grounded properly for both personnel and equipment safety.
Always ensure that facility AC input power is de-energized prior to connecting or disconnecting any
cable.
In normal operation, the operator does not have access to hazardous voltages within the chassis.
However, depending on the user’s application configuration, HIGH VOLTAGES HAZARDOUS TO
HUMAN SAFETY may be normally generated on the output terminals. The customer/user must ensure
that the output power lines are labeled properly as to the safety hazards and that any inadvertent contact
with hazardous voltages is eliminated.
Guard against risks of electrical shock during open cover checks by not touching any portion of the
electrical circuits. Even when power is off, capacitors may retain an electrical charge. Use safety glasses
during open cover checks to avoid personal injury by any sudden component failure.
Neither AMETEK Programmable Power Inc., San Diego, California, USA, nor any of the subsidiary sales
organizations can accept any responsibility for personnel, material or inconsequential injury, loss or
damage that results from improper use of the equipment and accessories.

Sequoia Series 5
SAFETY SYMBOLS

6 Sequoia Series
Product Family: Sequoia Series Power Source
Warranty Period: 2 Years
WARRANTY TERMS
AMETEK Programmable Power, Inc. (“AMETEK”), provides this written warranty covering the Product
stated above, and if the Buyer discovers and notifies AMETEK in writing of any defect in material or
workmanship within the applicable warranty period stated above, then AMETEK may, at its option:
repair or replace the Product; or issue a credit note for the defective Product; or provide the Buyer with
replacement parts for the Product.
The Buyer will, at its expense, return the defective Product or parts thereof to AMETEK in accordance
with the return procedure specified below. AMETEK will, at its expense, deliver the repaired or
replaced Product or parts to the Buyer. Any warranty of AMETEK will not apply if the Buyer is in default
under the Purchase Order Agreement or where the Product, or any part thereof, is as follows:
•damaged by misuse, accident, negligence or failure to maintain the same as
specified or required by AMETEK;
•damaged by modifications, alterations or attachments thereto which are not
authorized by AMETEK;
•installed or operated contrary to the instructions of AMETEK;
•opened, modified, or disassembled in any way without AMETEK’s consent;
•used in combination with items, articles or materials not authorized by AMETEK.
The Buyer may not assert any claim that the Products are not in conformity with any warranty until
the Buyer has made all payments to AMETEK provided for in the Purchase Order Agreement.
PRODUCT RETURN PROCEDURE
•Request a Return Material Authorization (RMA) number from the repair facility
(must be done in the country in which it was purchased)
•In the USA, contact the AMETEK Repair Department prior to the return of the
product to AMETEK for repair
•Telephone: [phone], ext. 2295 or ext. 2463 (toll free North America)
858-450-0085, ext. 2295 or ext. 2463 (direct)
•Outside the United States, contact the nearest Authorized Service Center (ASC). A
full listing can be found either through your local distributor or our website,
www.programmablepower.com, by clicking Support and going to the Service
Centres tab.
•When requesting an RMA, have the following information ready:
•Model number
•Serial number
•Description of the problem
NOTE: Unauthorized returns will not be accepted and will be returned at the shipper’s expense.
NOTE: A returned product found upon inspection by AMETEK, to be in specification is subject to an
evaluation fee and applicable freight charges.

Sequoia Series 7
Table of Contents
1. Introduction...................................................................................................................................10
1.1 Documentation Summary..................................................................................................10
1.2 External References..........................................................................................................10
1.3 Introduction to Programming.............................................................................................11
2. Introduction to SCPI......................................................................................................................14
2.1 Conventions Used in This Manual ....................................................................................14
2.2 The SCPI Commands and Messages...............................................................................14
2.3 Using Queries....................................................................................................................17
2.4 Structure of a SCPI Message............................................................................................17
2.5 SCPI Data Formats...........................................................................................................21
3. System Considerations and Interface Setup ................................................................................22
3.1 Assigning the IEEE-488 Address......................................................................................22
3.2 IEEE-488 Controllers ........................................................................................................22
3.3 RS232C Interface..............................................................................................................23
3.4 USB Interface....................................................................................................................26
3.5 LAN Interface Option.........................................................................................................29
4. SCPI Command Reference ..........................................................................................................33
4.1 Introduction........................................................................................................................33
4.2 Calibration Subsystem ......................................................................................................33
4.3 Instrument Subsystem ......................................................................................................48
4.4 Array Measurement Subsystem........................................................................................50
4.5 Current Measurement Subsystem ....................................................................................57
4.6 Frequency Measurement Subsystem ...............................................................................61
4.7 Phase Measurement Subsystem......................................................................................61
4.8 Power Measurement Subsystem......................................................................................62
4.9 Voltage Measurement Subsystem....................................................................................64
4.10 Output Subsystem.............................................................................................................67
4.11 Source Subsystem - Current.............................................................................................73
4.12 Source Subsystem –Power (eLoad Power Programming) ..............................................76
4.13 Source Subsystem -Impedance (eLoad RLC Programming) ...........................................77
4.14 Source Subsystem - Frequency........................................................................................78
4.15 Source Subsystem - Function...........................................................................................81
4.16 Source Subsystem –Synchronize (eLoad Mode).............................................................83
4.17 Source Subsystem –Program (eLoad Mode)...................................................................84
4.18 Regenerate Subsystem –Grid Simulator mode ...............................................................85
4.19 Source Subsystem - Limit.................................................................................................88
4.20 Sense Subsystem - Sweep...............................................................................................90
4.21 Source Subsystem - List ...................................................................................................92
4.22 Source Subsystem - Mode..............................................................................................100
4.23 Source Subsystem - Phase.............................................................................................101
4.24 Source Subsystem - PONSetup......................................................................................103
4.25 Source Subsystem - Pulse..............................................................................................111
4.26 Source Subsystem - Voltage...........................................................................................114
4.27 Status Subsystem Commands........................................................................................120
4.28 System Commands.........................................................................................................125
4.29 Trace Subsystem Commands.........................................................................................136
4.30 Trigger Subsystem..........................................................................................................138
5. Common Commands..................................................................................................................144
5.1 *CLS................................................................................................................................144
5.2 *ESE................................................................................................................................145

8 Sequoia Series
5.3 *ESR? ............................................................................................................................. 145
5.4 *IDN?............................................................................................................................... 146
5.5 *OPC............................................................................................................................... 146
5.6 *OPT? ............................................................................................................................. 147
5.7 *PSC ............................................................................................................................... 148
5.8 *RCL................................................................................................................................ 148
5.9 *RST................................................................................................................................ 149
5.10 *SAV................................................................................................................................ 150
5.11 *SRE ............................................................................................................................... 150
5.12 *STB?.............................................................................................................................. 150
5.13 *TRG............................................................................................................................... 151
5.14 *WAI................................................................................................................................ 151
5.15 *TST................................................................................................................................ 152
6. Programming Examples ............................................................................................................. 154
6.1 Introduction ..................................................................................................................... 154
6.2 Programming the Output................................................................................................. 154
6.3 Coupled Commands ....................................................................................................... 160
6.4 Programming Output Transients..................................................................................... 161
6.5 Triggering Output Changes............................................................................................. 166
6.6 Acquiring Measurement Data ......................................................................................... 169
6.7 Controlling the Instantaneous Voltage and Current Data Buffers................................... 175
6.8 Trigger System Summary ............................................................................................... 177
7. Status Registers ......................................................................................................................... 178
7.1 Power-On Conditions...................................................................................................... 178
7.2 Operation Status Group.................................................................................................. 178
7.3 Questionable Status Group............................................................................................. 181
7.4 Standard Event Status Group......................................................................................... 181
7.5 Status Byte Register ....................................................................................................... 181
7.6 Examples ........................................................................................................................ 182
7.7 SCPI Command Completion........................................................................................... 183
8. Option Commands...................................................................................................................... 184
8.1 Introduction ..................................................................................................................... 184
8.2 IEC 1000-4-11 (-411)...................................................................................................... 185
8.3 IEC 1000-4-13 (-413)...................................................................................................... 189
8.4 RTCA/DO-160D (-160) ................................................................................................... 201
8.5 MIL-STD 704E (-704)...................................................................................................... 208
8.6 Airbus ABD0100.1.8 Test Option (-ABD)........................................................................ 210
8.7 Airbus A350 ABD0100.1.8.1 Test Option (-A350).......................................................... 210
8.8 Airbus AMD24 Test Option (-AMD)................................................................................. 210
8.9 Boeing B787-0147 Test Option (-B787) ......................................................................... 210
8.10 Watt Hour Meter (-WHM)................................................................................................ 210
Appendix A: SCPI Command tree .................................................................................................... 213
Appendix B: SCPI Conformance Information.................................................................................... 218
Appendix C: Error Messages............................................................................................................ 219
Index.................................................................................................................................................. 225

Sequoia Series 9
Table of Figures
Figure 2-1 : Partial Command Tree.....................................................................................................................15
Figure 2-2: Command Message Structure...........................................................................................................18
Figure 3-1: DB25 to DB9 Adaptor pinout.............................................................................................................25
Figure 3-2: GUI Interface Settings for use of USB port........................................................................................29
Figure 3-3: Pinging AC Source LAN IP address..................................................................................................31
Figure 6-1: Output transient system ..................................................................................................................162
Figure 6-2: Transient Trigger System Model .....................................................................................................166
Figure 6-3: Measurement Acquisition Trigger Model.........................................................................................173
Figure 6-4: Pre-event and Post-event Triggering...............................................................................................176
Figure 6-5: Trigger system block diagram .........................................................................................................177
Figure 7-1: Status System Model ......................................................................................................................179
Table of Tables
Table 3-1. RS-232C Interface Connector Pinout.................................................................................................23
Table 4-1 : PULSe:HOLD = WIDTh parameters...............................................................................................112
Table 4-2 : PULSe:HOLD = DCYCle parameters..............................................................................................112
Table 5-1 : *RST default parameter values .......................................................................................................149
Table 5-2 : Self-Test Error.................................................................................................................................152
Table 7-1: Operation Status Register................................................................................................................178
Table 7-2: Configuration of Status Register.......................................................................................................180
Table 7-3: Questionable Status Register...........................................................................................................181
Table 8-1 : Error Messages...............................................................................................................................223

10 Sequoia Series
1. Introduction
Programming details for the Sequoia Power Source are provided in this document. Listed below are
the chapters of this manual:
Chapter 1
Introduction
Chapter 2
Introduction to SCPI
Chapter 3
System Considerations and Interface Setup
Chapter 4
SCPI Command Reference
Chapter 5
Common Commands
Chapter 6
Programming Examples
Chapter 7
Status Registers
Chapter 8
Option Commands
Appendix A
SCPI command tree.
Appendix B
SCPI conformance information.
Appendix C
Error messages
1.1 Documentation Summary
This SCPI programming manual covers the California Instruments Sequoia power sources. A separate
User Manual is also supplied with all models in this product series. For front panel operation and
general service and calibration information on these produces, please refer to the User Manual. The
programming manual covers issues related to operating the Sequoia Series remotely using an
instrument controller.
The following documents are related to this Programming Manual and contain additional helpful
information for using these products in a remote-control environment.
User Manual (M447352-01). Includes specifications and supplemental characteristics, how to use the
front panel, how to connect to the instrument, and calibration procedures. Available on the AMETEK
website www.programmablepower.com
1.2 External References
SCPI References
The following documents will assist you with programming in SCPI:
•Beginner's Guide to SCPI.
Highly recommended for anyone who has not had previous experience programming with SCPI.
IEEE-488 References
The most important IEEE-488 documents are your controller programming manuals -IEEE-488
Command Library for Windows®, etc. Refer to these for all non-SCPI commands (for example: Local
Device Clear and Group Execute Trigger bus commands.)
•IEEE-488 command library for Windows®.
•IEEE-488 controller programming
The following are two formal documents concerning the IEEE-488 interface:
•ANSI/IEEE Std. 488.1-1987 IEEE Standard Digital Interface for Programmable
Instrumentation. Defines the technical details of the IEEE-488 interface. While much of

Sequoia Series 11
the information is beyond the need of most programmers, it can serve to clarify the terms
used in this guide and related documents.
•ANSI/IEEE Std. 488.2-1987 IEEE Standard Codes, Formats, Protocols, and Common
Commands. Recommended as a reference only if you intend to do fairly sophisticated
programming. Helpful for finding precise definitions of certain types of SCPI message
formats, data types, or common commands.
The above two documents are available from the IEEE (Institute of Electrical and Electronics
Engineers), 345 East 47th Street, New York, NY 10017, USA.
1.3 Introduction to Programming
This section provides some general information regarding programming instrumentation and available
interface types.
1.3.1 IEEE-488 Capabilities of the Power Source
All power source functions are programmable over the Ethernet (LAN), USB, RS-232C, or optional
IEEE-488 interface bus.
IEEE-488 Address
The power source operates from a single IEEE-488 address that may be set from the front panel or
programmatically through the IEEE-488 bus. Care must be used when setting the IEEE-488 address
programmatically since the next statement sent to the source must reflect the new address.
1.3.2 USB Capabilities of the Power Source
All power source functions are programmable over the USB interface. Some capabilities that support
the IEEE-488 interface such as ATN, GET, and SRQ interrupts do not apply to the USB interface. The
USB interface operates internally at a fixed baud rate of 460800 baud, but USB 2.0 burst transfer rates
are supported. To set up the USB interface on the PC, refer to section 3.4, “USB Interface”.
The USB interface may be used to install the updated firmware for the controller if needed. Firmware
updates and a Flash Loader utility program and instructions are available from the AMETEK
Programmable Power website for this purpose. (www.programmablepower.com).
Multiple USB connections to the same PC:
The Windows driver used to interface to the power source’s USB port emulates a serial com port. This
virtual com port driver cannot differentiate between multiple units so, the use of more than one power
source connected to the same PC via USB is not recommended. The use of the GPIB interface is
recommended for these situations.
1.3.3 LAN Capabilities of the Power Source
All power source functions are programmable over the LAN (Ethernet) interface. Some capabilities
that support the IEEE-488 interface such as ATN, GET and SRQ interrupts do not apply to the LAN
interface. The LAN interface operates internally at a fixed baud rate of 460800 baud but autodetection
of 10Base-T, 100Base-T, and 1000Base-T is supported. To set up the LAN interface on a PC, refer to
section 3.5, “LAN Interface Option”.
The LAN interface may be used to install the updated firmware for the controller if needed. Firmware
updates and a Flash Loader utility program and instructions are available from the AMETEK
Programmable Power website for this purpose. (www.programmablepower.com).

12 Sequoia Series
1.3.4 RS232C Capabilities of the Power Source
All power source functions are programmable over the RS232C interface. Some capabilities that
support the IEEE-488 interface such as ATN, GET and SRQ interrupts do not apply to the RS232C
interface. Baud rates from 9600 to 115200 are supported on units that have both USB and RS232. To
set up the RS232C interface, refer to section 3.3.
The RS232C interface may be used to install the updated firmware for the controller if needed.
Firmware updates and a Flash Loader utility program and instructions are available from the AMETEK
Programmable Power website for this purpose. (www.programmablepower.com).

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This page is intentionally left blank.

14 Sequoia Series
2. Introduction to SCPI
SCPI (Standard Commands for Programmable Instruments) is a programming language for controlling
instrument functions over the IEEE-488. SCPI is layered on top of the hardware-portion of IEEE 488.1.
The same SCPI commands and parameters control the same functions in different classes of
instruments. For example, you would use the same MEAS:VOLT? command to measure the power
source output voltage or the output voltage measured using an SCPI-compatible multimeter.
2.1 Conventions Used in This Manual
Angle brackets<> Items within angle brackets are parameter abbreviations. For
example, <NR1> indicates a specific form of numerical data.
Vertical bar Vertical bars separate alternative parameters. For example, FIX |
STEP indicates that either "FIX" or "STEP" can be used as a
parameter.
Square Brackets [ ] Items within square brackets are optional. The representation
[SOURce:]LIST means that SOURce: may be omitted.
Braces Braces indicate parameters that may be repeated zero or more
times. It is used especially for showing arrays. The notation <A>
<,B> shows that parameter "A" must be entered, while parameter
"B" may be omitted or may be entered one or more times.
Boldface font Boldface font is used to emphasize syntax in command definitions.
TRIGger:SOURCe<NRf> shows a command definition.
Computer font Computer font is used to show program lines in text.
TRIGger:SOURCe INT
shows a program line.
2.2 The SCPI Commands and Messages
This paragraph explains the syntax difference between SCPI Commands and SCPI messages.
2.2.1 Types of SCPI Commands
SCPI has two types of commands, common and subsystem.
•Common commands are generally not related to specific operations but to controlling
overall power source functions such as reset, status, and synchronization. All common
commands consist of a three-letter mnemonic preceded by an asterisk:
*RST
*IDN?
*SRE 256
•Subsystem commands perform specific power source functions. They are organized into
an inverted tree structure with the "root" at the top. Some are single commands while
others are grouped within specific subsystems.
Refer to appendix A for the power source SCPI tree structure.

Sequoia Series 15
2.2.2 Types of SCPI Messages
There are two types of SCPI messages, program, and response.
•A program message consists of one or more properly formatted SCPI commands sent
from the controller to the power source. The message, which may be sent at any time,
requests the power source to perform some action.
•A response message consists of data in a specific SCPI format sent from the power source
to the controller. The power source sends the message only when commanded by a
program message called a "query."
2.2.3 The SCPI Command Tree
As previously explained, the basic SCPI communication method involves sending one or more properly
formatted commands from the SCPI command tree to the instrument as program messages. The
following figure shows a portion of a subsystem command tree, from which you access the commands
located along the various paths (you can see the complete tree in appendix A).
Root
:OUTPut
:PON
:TTLTrg
:IMPedance
:OPERation
:SOURce
:REAL
:REACtive
:STATus
[:STATe]
[:STATe]
[:EVEN]?
:CONDition?
Figure 2-1 : Partial Command Tree
The Root Level
Note the location of the ROOT node at the top of the tree. Commands at the root level are at the top
level of the command tree. The SCPI interface is at this location when:
•The power source is powered on
•A device clear (DCL) is sent to the power source
•The SCPI interface encounters a message terminator
•The SCPI interface encounters a root specifier
Active Header Path
In order to properly traverse the command tree, you must understand the concept of the active header
path. When the power source is turned on (or under any of the other conditions listed above), the
active path is at the root. That means the SCPI interface is ready to accept any command at the root
level, such as SOURCe or MEASurement
If you enter SOURCe the active header path moves one colon to the right. The interface is now ready
to accept :VOLTage :FREQuency, or :CURRent as the next header. You must include the colon
because it is required between headers.

16 Sequoia Series
If you now enter :VOLTage, the active path again moves one colon to the right. The interface is now
ready to accept either :RANGe or :LEVel as the next header.
If you now enter :RANGe you have reached the end of the command string. The active header path
remains at :RANGe If you wished, you could have entered :RANGe 166 ;LEVel 115 and it would be
accepted as a compound message consisting of:
SOURce:VOLTage:RANGe 166.
SOURce:VOLTage:LEVel 115.
The entire message would be:
SOURce:VOLTage:RANGe 166;LEVel 115
The message terminator after LEVel 115 returns the path to the root.
The Effect of Optional Headers
If a command includes optional headers, the interface assumes they are there. For example, if you
enter [SOURCe]:VOLTage 115, the interface recognizes it as [SOURce]:VOLTage:LEVel 115. This
returns the active path to the root (:VOLTage). But if you enter [SOURce]:VOLTage:LEVel 115 then
the active path remains at :LEVel This allows you to send
[SOURce]:VOLTage:LEVel 115;RANGe 166
in one message. If you did not send LEVel you are allowed to send the following command:
[SOURce]:VOLTage 115;FREQuency 60
The optional header [SOURce] precedes the current, frequency, function, phase, pulse, list, and
voltage subsystems. This effectively makes :CURRent,:FREQuency, :FUNCtion, :PHASe, :PULse,
:LIST, and :VOLTage root-level commands.
Moving Among Subsystems
In order to combine commands from different subsystems, you need to be able to restore the active
path to the root. You do this with the root specifier (:). For example, you could open the output relay
and check the status of the Operation Condition register as follows:
OUTPut:STATe ON
STATus:OPERation:CONDition?
Because the root specifier resets the command parser to the root, you can use the root specifier and
do the same thing in one message:
OUTPut on; :STATus:OPERation:CONDition?
The following message shows how to combine commands from different subsystems as well as within
the same subsystem:
VOLTage:RANGe 116;LEVel 115;:CURRent 10;PROTection:STATe ON
Note the use of the optional header LEVel to maintain the correct path within the voltage and current
subsystems and the use of the root specifier to move between subsystems. The "Enhanced Tree
Walking Implementation" given in appendix A of the IEEE 488.2 standard is not implemented in the
power source.

Sequoia Series 17
Including Common Commands
You can combine common commands with system commands in the same message. Treat the
common command as a message unit by separating it with a semicolon (the message unit separator).
Common commands do not affect the active header path; you may insert them anywhere in the
message.
VOLTage:TRIGger 7.5;*TRG
OUTPut OFF;OUTPut ON;*RCL 2
2.3 Using Queries
Observe the following precautions with queries:
•Set up the proper number of variables for the returned data.
•Read back all the results of a query before sending another command to the power
source. Otherwise, a Query Interrupted error will occur and the unreturned data will be
lost.
2.4 Structure of a SCPI Message
SCPI messages consist of one or more message units ending in a message terminator. The terminator
is not part of the syntax, but implicit in the way your programming language indicates the end of a line
(such as a newline or end-of-line character).
2.4.1 The Message Unit
The simplest SCPI command is a single message unit consisting of a command header (or keyword)
followed by a message terminator.
FREQuency?<newline>
VOLTage?<newline>
The message unit may include a parameter after the header. The parameter usually is numeric, but it
can be a string:
VOLTage 20<newline>
VOLTage MAX<newline>

18 Sequoia Series
2.4.2 Combining Message Units
The following command message is briefly described here, with details in subsequent paragraphs.
Figure 2-2: Command Message Structure
The basic parts of the above message are:
Message Component
Example
Headers
VOLT LEV RANG CURR
Header Separator
The colon in VOLT:LEV
Data
8 166
Data Separator
The space in VOLT 8 and RANG 166
Message Units
VOLT:LEV 8 RANG 166 CURR?
Message Unit Separator
The semicolons in VOLT:LEV 8; and RANG 166;
Root Specifier
The colon in RANG 166;:CURR?
Query Indicator
The question mark in CURR?
Message Terminator
The <NL> (newline) indicator. Terminators are not part of the
SCPI syntax

Sequoia Series 19
2.4.3 Headers
Headers are instructions recognized by the power source. Headers (which are sometimes known as
"keywords") may be either in the long form or the short form.
Long Form
The header is completely spelled out, such as VOLTAGE,
STATUS, and OUTPUT.
Short Form
The header has only the first three or four letters, such as
VOLT, STAT, and OUTP.
The SCPI interface is not sensitive to case. It will recognize any case mixture, such as TRIGGER,
Trigger, TRIGger. Short form headers result in faster program execution.
Header Convention
In the command descriptions in Chapter 3.4 of this manual, headers are emphasized with boldface
type. The proper short form is shown in upper-case letters, such as DELay.
Header Separator
If a command has more than one header, you must separate them with a colon (VOLT:LEVel
OUTPut:RELay ON).
Optional Headers
The use of some headers is optional. Optional headers are shown in brackets, such as
OUTPut[:STATe] ON. As previously explained under "The Effect of Optional Headers", if you combine
two or more message units into a compound message, you may need to enter the optional header.
2.4.4 Query Indicator
Following a header with a question mark turns it into a query (VOLTage?, VOLTage:RANGe?). If a
query contains a parameter, place the query indicator at the end of the last header (VOLTage:LEVel?
MAX).
2.4.5 Message Unit Separator
When two or more message units are combined into a compound message, separate the units with a
semicolon (STATus:OPERation?;QUEStionable?).

20 Sequoia Series
2.4.6 Root Specifier
When it precedes the first header of a message unit, the colon becomes the root specifier. It tells the
command parser that this is the root or the top node of the command tree. Note the difference between
root specifiers and header separators in the following examples:
CURRent:PROTection:DELay .1
All colons are header separators
:CURRent:PROTection:DELay .1
Only the first colon is a root
specifier
CURRent:PROTection:DELay .1;:VOLTage 12.5
Only the third colon is a root
specifier
You do not have to precede root-level commands with a colon; there is an implied colon in front of
every root-level command.
2.4.7 Message Terminator
A terminator informs SCPI that it has reached the end of a message. Three permitted message
terminators are:
•newline (<NL>), which is ASCII decimal 10 or hex 0A.
•end or identify (<END>)
•both of the above (<NL><END>).
In the examples of this manual, there is an assumed message terminator at the end of each message.
If the terminator needs to be shown, it is indicated as <NL> regardless of the actual terminator
character.