advertisement
RS-232 Transducer
Digital Communication
User’s Manual
Firmware Version 217928G
Stellar Technology Incorporated
Copyright Notice
© 2004 Stellar Technology Incorporated. All rights reserved.
This manual, as well as the software described in it, is furnished under license and may be used or copied only in accordance with the terms of such license. The content of this manual is furnished for informational use only, is subject to change without notice, and should not be construed as a commitment by Stellar Technology Incorporated. Stellar Technology Incorporated assumes no responsibility or liability for any errors or inaccuracies that may appear in this book.
Except as permitted by such license, no part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, recording, or otherwise, without the prior written permission of Stellar Technology Incorporated.
it2000 is a trademarks of Stellar Technology Incorporated. it2000 logo and the STI logo are trademarks of Stellar Technology Incorporated in the USA. Microsoft, Windows 9x/NT/2000/XP/
CE, Microsoft Access, and Microsoft Excel are registered trademarks of Microsoft Corporation. All other products or name brands are the trademarks of their respective holders.
Part number: 222133 Rev A
Contents
iv
RS-232 Transducer Digital Communication User’s Manual
C H A P T E R 1
Installation
This chapter describes the steps to install the RS-232 Transducer.
Contents
• RS-232 Connector .........................................................................6
• Communication Setup .................................................................7
6
RS-232 Transducer Digital Communication User’s Manual
RS-232 Connector
Serial data is transmitted and received using only three signals of the RS-232 connector. All digital output signals are galvanically isolated from the transducer excitation supply.
5
9
4 3
8 7
2
6
1
Pin 2 - TxD
Pin 3 - RxD
Pin 5 - D
GND
Figure 1-1: RS-232 pin assignments
Chapter 1: Installation
Communication Setup
The RS-232 Transducer uses an RS-232 interface as a means of communication with a controller. The default communication parameters are as follows:
Setting
Baud rate
Data bits
Stop bits
Parity
Flow control
Value
9600
8
1 none none
Table 1-1: RS-232 communication settings
Commands are sent in ASCII text using the syntax described Chapter 3, “Using
Commands”. All commands must be terminated with a carriage-return / line-feed combination or a line-feed-only character sequence.
7
8
RS-232 Transducer Digital Communication User’s Manual
C H A P T E R 2
Quick-Start Tutorial
This chapter gives you a quick guide on how to connect Series it2000 Pressure
Transducer and start using it’s basic functionality.
Contents
• Basic Measurements .....................................................................10
10
RS-232 Transducer Digital Communication User’s Manual
Basic Measurements
To make basic digital pressure or temperature measurements you may use the standard Windows Terminal program with appropriate settings.
Steps required to make one digital pressure measurement using the Terminal program:
1.
Run Terminal program
2.
Set communication port settings
3.
Type in the command: meas:pres? terminated with the command terminator
(see Chapter 3, “Using Commands”)
4.
An example of a RS-232 Transducer response is shown below.
Figure 2-1: Windows Terminal program
For more commands see Chapter 4, “Command Reference”.
C H A P T E R 3
Using Commands
The RS-232 Transducer is controlled through the RS-232 interface using a large group of commands and queries. This chapter describes the syntax these commands and queries use and the conventions the transducer uses to process them. The commands and queries themselves are listed in Chapter 4, “Command
Reference”.
Contents
• Command and Query Structure ...................................................16
• Command Entry ............................................................................17
• Argument Types ............................................................................18
• Command Usage Rules .................................................................20
• Syntax Diagrams ............................................................................20
12
RS-232 Transducer Digital Communication User’s Manual
Commands are transmitted to the transducer using the American Standard Code for Information Interchange (ASCII) character encoding.
This manual uses Backus-Naur Form (BNF) notation and syntax diagrams to describe commands and queries. The following BNF symbols:
Symbol
< >
::=
|
{}
[]
...
()
Meaning
Defined element
Is defined as
Exclusive OR
Group; one element is required
Optional; can be omitted
Previous element(s) may be repeated
Comment
Table 3-1: BNF Symbols and Meanings
Command and Query Structure
Commands consist of set commands and query commands (usually simply called commands and queries). Commands modify instrument settings or tell the transducer to perform a specific action. Queries cause the transducer to return data and information about its status.
Most commands have both a set form and a query form. The query form of the command is the same as the set form but with a question mark at the end. For example, the set command INPut:GAIN has a query form INPut:GAIN?. Not all commands have both a set and a query form; some commands are set only and some are query only.
A command message is a command or query name, followed by any information the transducer needs to execute the command or query. Command messages consist of five different element types, defined as follows:
Symbol
<Header>
<Mnemonic>
Meaning
The basic command name. If the header ends with a question mark, the command is a query. The header may begin with a colon (:) character; if the command is concatenated with other commands the beginning colon is required. The beginning colon can never be used with a command beginning with an asterisk (*).
A header sub-function. Some commands headers have only one mnemonic. If a command header has multiple mnemonics, they are always separated from each other by a colon (:) character.
Chapter 3: Using Commands 13
Symbol
<Argument>
<Comma>
<Space>
Meaning
A quantity, quality, restriction, or limit associated with the header. Not all commands have multiple arguments. Arguments are separated from the header by a <Space>. Arguments are separated from each other by a
<Comma>.
A single comma between arguments of multipleargument commands. It may optionally have white space characters before and after the comma.
A white space character between command header and argument. It may optionally consist of multiple white space characters.
Table 3-2: Command Message Elements
Header
WORKset:DEFAult SAMPLE,ON
Comma
Mnemonics Space Arguments
WORKset : DEFAult <Space>
Figure 3-1: Command Message Elements
<name> <comma> <state>
Commands
Commands cause the transducer to perform a specific function or change one of its settings. Commands have the structure:
<Header>[<Space><Argument>[<Comma><Argument>]...]
A command header is made up of one or more mnemonics arranged in a hierarchical or tree structure. The first mnemonic is the base or root of the tree and each subsequent mnemonic is a level or branch off the previous one.
Commands at a higher level in the tree may affect those at a lower level. The leading colon (:) always returns you to the base of the command tree.
Queries
Queries cause the transducer to return information about its status or settings.
Queries have the structure:
<Header>?
<Header>?[<Space><Argument>[<Comma><Argument>]...]
Command Entry
Follow these general rules when entering commands:
• Commands can be entered in upper or lower case.
14
RS-232 Transducer Digital Communication User’s Manual
• Any command can be preceded with white space characters. White space characters include any combination of the ASCII control characters 00 through 09 and 0B through 20 hexadecimal (0 through 9 and 11 through 32 decimal).
• The transducer ignores commands consisting of any combination of white space characters and line feeds.
Suffixes
Some mnemonics have a plural form. The mnemonic that is expressed in plural form indicates that it represents more than one instance of a subsystem. This is illustrated as follows:
TEST:INP5?
All suffixes have a default value of one and is used when the suffix is not specified.
Suffixes are enclosed in brackets in the command syntax descriptions to indicate their optional inclusion. The brackets are not to be included in actual usage.
Command Termination
All commands are terminated with a carriage-return / line-feed combination. The
SCPI specification also allows for the use of a line-feed character only. The ASCII codes for these command terminators are as follows:
ASCII Code
10
13
Key Stroke
Control + j
Control + m
Description
Line feed
Carriage return
Table 3-3: ASCII Codes for Command Termination
Argument Usage
All arguments listed for a command are mandatory and must be specified by at least a placeholder. Multiple arguments must be separated by a comma. String arguments are case-sensitive unless otherwise noted. Those arguments that are actually mnemonics themselves follow the same abbreviation options as described above.
Argument Types
The argument of a command may be in one of several forms. The individual descriptions of each command tell which argument types to use with that command.
Numeric Arguments
Many transducer commands require numerical arguments. The syntax shows the format that the transducer returns in response to a query. This is also the preferred format when sending the command to the transducer though it will accept any of the formats. This manual represents these arguments as follows:
Chapter 3: Using Commands 15
Symbol
<NR1>
<NR2>
<NR3>
Table 3-4: Numeric Argument Types
Meaning
Signed integer value
Floating point value without an exponent
Floating point value with an exponent
The transducer will automatically force most numeric arguments to a valid setting, either by rounding or truncating, when you input an invalid number unless otherwise noted in the command description.
Quoted String Arguments
Some commands accept or return data in the form of a quoted string, which is simply a group of ASCII characters enclosed by a double quote (“). For example:
“this is a quoted string”
Symbol
<QString>
Table 3-5: Quoted String Argument Type
Meaning
Quoted string value
Follow these rules when you use quoted strings:
• A quoted string can include any character defined in the 7-bit ASCII character set.
• Strings can have upper or lower case characters.
• A string cannot be terminated with the END message before the closing delimiter.
• The maximum length of a quoted string returned from a query is 256 characters.
Block Arguments
Some transducer commands use a block argument form:
Symbol
<NZDig>
<Dig>
<DChar>
<Block>
Meaning a non-zero digit character, in the range 1-9
A digit character, in the range 0-9
A character with the hex equivalent of 00 through FF hexadecimal (0 through 255 decimal)
A block of data bytes, defined as:
<Block> ::=
{ #<NZDig><Dig>[<Dig>...][<DChar>...]
| #0[<DChar>...]<terminator> }
Table 3-6: Block Argument Types
16
RS-232 Transducer Digital Communication User’s Manual
<NZDig> specifies the number of <Dig> elements that follow. Taken together, the
<Dig> elements form a decimal integer that specifies how many <DChar> elements follow.
Command Usage Rules
It is important to keep the following rules in mind when using the commands in this reference guide:
1.
Commands are case-insensitive.
2.
All commands are terminated by a carriage-return / line-feed combination or a linefeed.
3.
All arguments are required.
4.
Multiple arguments must be separated by a comma.
5.
String arguments are case-sensitive unless they are a mnemonic.
Syntax Diagrams
The syntax diagrams in this manual use the following symbols and notation:
• Circles and ovals contain literal elements. Most elements must be sent exactly as shown. The diagrams show command mnemonics in both upper and lower case to distinguish between complete and abbreviated spellings.
These elements are not case sensitive and you can omit the lower case portion of the mnemonic.
• Boxes contain the defined elements described earlier in this section, such as
<NR3> or <QString>.
• Elements are connected by arrows that show the allowed paths through the diagram, and thus the orders in which you can send the elements. Parallel paths show that you must take one and only one of the paths. A path around a group of elements shows that those elements are optional. Loops show elements that can be repeated.
Here are some examples of typical syntax diagrams:
C H A P T E R 4
Command Reference
This chapter describes each of the commands used to configure and control the
RS-232 Transducer. The command reference is broken down into several groups of related functionality.
Contents
• Measure Subsystem ......................................................................20
• Test Commands ............................................................................22
• System Commands .......................................................................24
18
RS-232 Transducer Digital Communication User’s Manual
Measure Subsystem
The measure subsystem includes commands for initiating pressure and temperature measurements.
MEAS:PRES
Returns a pressure measurement.
Syntax MEAS:PRES?
MEAS : PRES ?
Remarks The unit of measure is PSI.
Pressure output is fixed at 7 characters, with a first sign character followed by a number with resolution based on a following table:
Pressure range
0<=Range<5
5<=Range<50
50<=Range<500
500<=Range<5000
5000<=Range
Example meas:pres?
+14.135
Output format
±0.0000
±00.000
±000.00
±0000.0
±000000
Chapter 4: Command Reference
MEAS:TEMP
Returns a temperature measurement.
Syntax MEAS:TEMP[channel]?
MEAS : TEMP channel ?
Suffix channel
Parameter none
0
1
Result
Temperature from the on-chip temperature sensor
(default)
Temperature from the on-chip temperature sensor
Temperature from the RTD (optional)
Remarks The unit of measure is degrees Fahrenheit.
Temperature output is fixed to the following format: ±000.00
Example meas:temp?
+078.91
19
MEAS:ALL
Returns a pressure and temperature measurements.
Syntax MEAS:ALL?
MEAS : ALL ?
Remarks First value - pressure measurement, second value - on-chip temperature measurement or RTD temperature if there is one present, third value (optional) - on-chip temperature measurement if RTD is present.
Example meas:all?
+078.50,+123.24
20
RS-232 Transducer Digital Communication User’s Manual
Test Commands
Test commands allow to calibrate digital and analog output of the Series it2000 pressure transducer.
TEST:INP
Reads digital counts from selected channels.
Syntax TEST:INP[channel]?
TEST : INP channel ?
Suffix channel
Possible values: 5
Parameter
5
Result
Digital pressure and temperature counts, Board temperature
Remarks Temperature measurement is the RTD temperature if there is one present, otherwise it is the temperature from the on-chip temperature sensor.
Board temperature is the temperature from the on-chip temperature sensor expressed in degrees Celcius.
Example test:inp5?
11775507,41600,34.5
TEST:OUTPV
Sets analog voltage output corresponding to a given count.
Syntax TEST:OUTPV count
TEST : OUTPV <Space> count
Parameters count
Possible values: 0-4095
Chapter 4: Command Reference
The count is a value which will be send to the digital-to-analog converter to set the analog output.
Remarks This command is used to calibrate a transducer’s analog output during the factory calibration process.
Example test:outpv 2768
21
22
RS-232 Transducer Digital Communication User’s Manual
System Commands
System commands includes those relating to identification, resetting the unit, setting a timer.
SYST:VERS:FIRM
Returns the firmware version.
Syntax SYST:VERS:FIRM?
SYST :
Example syst:vers:firm?
217928G
VERS : FIRM ?
*IDN
Returns the transducer part number, serial number and a revision.
Syntax *IDN?
*IDN ?
Example *idn?
STELLAR TECHNOLOGY INC,IT2000-15A-101,007713,0
*RST
Resets the it2000 to power-up status.
Syntax *RST
*RST
Remarks Executing this command is equivalent to executing a power-up sequence.
Example *rst
Chapter 4: Command Reference
OFFSET:SET
Sets or returns the value for the input offset.
Syntax OFFSET:SET offset
OFFSET:SET?
OFFSET : SET
<Space>
?
value
Parameters offset
Real numeric value.
This signed value will be added to the digital output prior to displaying it.
Input offset will also affect the analog output.
Remarks Input offset value is always in PSI.
Example offset:set 3.4
offset:set?
3.40
23
SPAN:SET
Sets or returns the value for the span.
Syntax SPAN:SET span
SPAN:SET?
SPAN : SET
<Space>
?
value
Parameters span
Real numeric value from (0..150] interval.
The pressure transducer’s span will be set to the span% of the original value.
Remarks Default value is 100.
Example span:set 101
If the pressure transducer has 0-5 V output at 0-100 PSIG, after setting span=101 analog output will be 0-5.05 V at 0-100 PSIG. Digital output will be
0-101 PSIG.
span:set?
101.00
24
RS-232 Transducer Digital Communication User’s Manual
TURNDOWN:SET
Sets or returns the value for the turndown.
Syntax TURNDOWN:SET turndown
TURNDOWN:SET?
TURNDOWN : SET
<Space>
?
value
Parameters turndown
Real numeric value from [1..100] interval.
The pressure transducer’s pressure range will be set to the turndown% of the original value.
Remarks Default value is 100.
Example turndown:set 50
If the pressure transducer has 0-5 V output at 0-200 PSIG, after setting turndown=50 output will be 0-5 V at 0-100 PSIG. Digital pressure measurement is not affected.
turndown:set?
50.000
TIMER:SET
Sets or returns timer settings. The it2000 will send pressure and temperature readings over a RS-232 in the specified time interval.
Syntax TIMER:SET type, value
TIMER:SET?
?
TIMER : SET
<Space> type <comma> value
Parameters type
This value specifies a time interval type.
Possible values: 0-3.
Parameter
2
3
0
1
Result
Interval measured in 1/128 of a second
Interval measured in seconds
Interval measured in minutes
Interval measured in hours
Chapter 4: Command Reference value
Numeric value from 0 to 255.
This value determines a time interval in specified units of measure.
Remarks Value set to 0 will stop the timer function.
In 1/128 mode not every setting will result in a proper response rate due to the
IT2000 performance limitations.
Example timer:set 1, 100 timer:set?
sec,100
25
26
RS-232 Transducer Digital Communication User’s Manual
Index
Symbols
* (asterisk)
: (colon)
,
A analog output
,
argument
Argument Types
Block Arguments
Numeric Arguments
Quoted String Arguments
ASCII (American Standard Code for
Information Interchange)
,
,
,
B
Backus-Naur Form (BNF)
Basic Measurements
C carriage-return
,
case lower
,
upper
channel
Command Entry
Argument Usage
Command Termination
Suffixes
Command Reference
Input Subsystem
INPut
OFFSet
VALUE
Measure Subsystem
MEASure
ALL
PRESsure
TEMPerature
UNIT
PRESsure
System Commands
*IDN
*RST
SYSTem
VERSion
FIRMware
Test Commands
TEST
INPut
OUTPV
Trigger Subsystem
TRIGger
PRESsure
Command Usage Rules
Commands and Query Structure
Commands
Queries
communication port
Communication Setup
D digital count
output
,
pressure
temperature
digital to analog converter
F firmware
G gain
L line-feed
M message
mnemonic
,
,
O offset input
output voltage
R
RS-232
S
Standard Commands for Programmable Instruments (SCPI)
suffix
Syntax Diagrams
W white space
Wiring Harness
RS-232 Connector
28
RS-232 Transducer Digital Communication User’s Manual
advertisement
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project