C&H Technologies EM405-8 User manual

Manual Part No: 11030574A
MODEL
EM405-8
SCRIPTING MANUAL
ETHERNET
M-MODULE
CARRIER/
BRIDGE

ii
COPYRIGHT
C&H Technologies, Inc. (C&H) provides this manual "as is" without warranty of any kind,
either expressed or implied, including but not limited to the implied warranties of
merchantability and fitness for a particular purpose. C&H may make improvements and/or
changes in the product(s) and/or program(s) described in this manual at any time and without
notice.
This publication could contain technical inaccuracies or typographical errors. Changes are
periodically made to the information herein; these changes will be incorporated in new editions
of this publication.
Copyright © 2009, 2012 by C&H Technologies, Inc.
The information and/or drawings set forth in this document and all rights in and to inventions
disclosed herein which might be granted thereon disclosing or employing the materials, methods,
techniques, or apparatus described herein, are the exclusive property of C&H Technologies, Inc.
A Reader's Comment Form is provided at the back of this publication. If this form has been
removed address comments to:
C&H Technologies, Inc.
Technical Publications
800 Paloma Drive, Suite 150
Round Rock, Texas 78665
C&H may use or distribute any of the information you supply in any way that it believes
appropriate without incurring any obligations whatever.

iii
DOCUMENT REVISION NOTICE
C&H Technologies, Inc. makes every attempt to provide up-to-date manuals with the associated
equipment. Occasionally, throughout the life of an instrument, changes are deemed necessary to
equipment related documentation. The latest revision of our documentation is available for
download from our web site at http://www.chtech.com.
NOTE
The contents of any amendment may affect operation,
maintenance, or calibration of the equipment.

iv
INTRODUCTION
This manual describes the operation and use of the scripting features of the EM405-8 Ethernet
M-Module Carrier/Bridge (Part Number 11029380). The scripting features described throughout
this manual are available on all EM405-8’s containing firmware version 3.0 and later. Contained
within this manual are the functional details and the programmatic guidelines to adequately
develop and deploy script-based applications for the EM405-8.
The EM405-8 is one of many test, data acquisition and control modules provided by C&H
Technology and is one of a number of M-Module carriers in C&H Technologies’ product line.
All manufacturing options of the EM405-8 include the scripting features; however, only options
that include an internal mass storage device provide non-volatile storage of scripts and
autonomous operation using the startup script feature.
The part numbers of the EM405-8’s that are covered by this manual are:
Part Number Description
11029380-0001 EM405-8 with external triggers
11029380-0002 EM405-8 without external triggers
11029380-0003 EM405-8 with external triggers and 16GB mass storage
11029380-0004 EM405-8 without external triggers, but with 16GB mass storage
EM405-8’s that contain a firmware revision prior to 3.0 can be updated in the field to the most recent firmware
revision containing the scripting support. Please contact C&H Technologies Technical Support for update files and
detailed instructions.

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TABLE OF CONTENTS
1.0 GENERAL DESCRIPTION ............................................................................................1
1.1 PURPOSE OF EQUIPMENT.............................................................................................2
1.2 THE LUA SCRIPTING LANGUAGE...............................................................................2
1.3 KEY FEATURES OF EM405-8 SCRIPTING ...................................................................2
1.4 APPLICABLE REFERENCES..........................................................................................3
2.0 USING AND MANAGING SCRIPTS ............................................................................4
2.1 COMMANDS..................................................................................................................... 4
2.1.1 ? | Help ......................................................................................................................... 4
2.1.2 Data.............................................................................................................................. 5
2.1.3 Halt............................................................................................................................... 5
2.1.4 List ...............................................................................................................................5
2.1.5 Read.............................................................................................................................6
2.1.6 Remove ........................................................................................................................ 6
2.1.7 Retrieve........................................................................................................................6
2.1.8 Run............................................................................................................................... 7
2.1.9 Socket?.........................................................................................................................8
2.1.10 Upload..........................................................................................................................8
2.1.11 Ver................................................................................................................................ 9
2.2 STORING SCRIPTS AND SUPPORTING FILES............................................................ 9
2.3 SCRIPTING SOCKET INTERFACE...............................................................................10
2.3.1 Configuring the Scripting Socket Interface ............................................................... 10
2.3.2 Connecting to the Scripting Socket Interface ............................................................11
2.3.3 Interactive Mode........................................................................................................11
3.0 DEVELOPING SCRIPTS.............................................................................................. 13
3.1 DEVELOPMENT SOFTWARE – EM405-8 IVI DRIVER SOFT FRONT PANEL......13
3.2 EM405-8 EXTENSIONS LIBRARY ............................................................................... 13
3.3 PASSING DATA.............................................................................................................. 20
3.4 CALLING M-MODULE DRIVERS................................................................................ 22
3.4.1 Using Alien to Call M-Module Drivers..................................................................... 22
3.4.2 Dealing with data.......................................................................................................25
3.4.2.1 Buffers................................................................................................................25
3.4.2.2 Arrays.................................................................................................................26
3.4.2.3 Pointer Unpacking..............................................................................................27
3.4.2.4 Callback Functions.............................................................................................27
3.4.3 Building M-Module Drivers into a Linux Shared Library......................................... 28
3.5 SHARING DATA BETWEEN SCRIPTS........................................................................28
3.6 STARTUP SCRIPT ..........................................................................................................28
3.7 USING THE MASS STORAGE DEVICE.......................................................................29
4.0 USING LUA TO WRITE CUSTOM WEB PAGES....................................................30
4.1 URL OF SCRIPT BASED PAGES.................................................................................. 30
4.2 ADDING A LINK TO THE C&H NAVIGATION MENU............................................. 31
4.3 URL OF PICTURES AND OTHER SUPPORTING FILES...........................................32
4.4 PASSING ARGUMENTS TO THE SCRIPT................................................................... 32
4.5 DEVELOPING THE PAGE CONTENT..........................................................................33

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LIST OF FIGURES
Figure 1 EM405-8 Scripting Utilities Architecture Diagram.........................................................1
Figure 2 Retrieve Script Download Format....................................................................................7
Figure 3 Script Upload Format.......................................................................................................9
Figure 4 Network Configuration Webpage ..................................................................................10
Figure 5 EM405-8 IVI Driver Scripting Panel Screenshot...........................................................13
Figure 6 Data Passing Example....................................................................................................21
Figure 7 M-Module Driver Example Code...................................................................................25
Figure 8 M-Module Driver Example Using Buffers ....................................................................26
Figure 9 M-Module Driver Example Using Arrays......................................................................27
Figure 10 Simple Lua Based Web Page .......................................................................................30
Figure 11 Example Adding Link to the Navigation Menu ...........................................................31
Figure 12 Example Linking to a User Image.................................................................................32
Figure 13 Example Retrieving Arguments from the URL ............................................................33
Figure 14 Example Using “l_em405web.lua” Library..................................................................35
LIST OF TABLES
Table I Use and Management Commands......................................................................................4
Table II. Functions in the EM405-8 Extensions Library..............................................................14
Table III. Alien Data Types ..........................................................................................................23
Table IV l_em405web.lua Library Functions................................................................................33

1
1.0 GENERAL DESCRIPTION
The scripting utilities of the EM405-8 M-Module Bridge provide enhanced programming
capabilities allowing the user to easily embed software on the bridge to improve performance
and further integrate a set of M-modules. The scripting utilities are based off of the Lua
programming language and include extensions and customizations designed specifically for the
EM405-8. An architecture diagram of the scripting utilities is shown in Figure 1. Since Lua is
an interpretive language, EM405-8 users can easily develop scripts without the need for an
expensive development environment.
By embedding a script or a set of scripts on the EM405-8, the burden for monitoring, configuring
and controlling the M-modules is taken off the network and placed onto the EM405-8’s embedded
processor. This provides significant performance improvements and allows the EM405-8 and
associated M-modules to be customized and configured. It can also act independently for a long
period of time without the need for a network client to monitor the device(s).
Figure 1EM405-8 Scripting Utilities Architecture Diagram
PART OF SCRIPTING EN
VIRONMENTFURNISHED
BYC&H
APPLICATION SPECIFIC
CUSTOMER DEVELOPMEN
T
HARDWARE
STANDARD AVAILABLE S
OFTWARE FROM C&H OR
THIRD PARTY
M-MODULES
EM405
-
8 UTILITIES
(TRIGGERS, FANS, ETC.)
EM405
-
8 LUA EXTENSIONS
M
-
MODULE ANSI
-
C DRIVERS
SCRIPTS
LUA STD LIBRARIES
ALIEN LIB
MASS STORAGE
EM405
-
8 SCRIPT MANAGEMENT
EM405
-
8 IVI DRIVER
DEVELOP SCRIPTS
MANAGE SCRIPTS
RUN SCRIPTS
VIEW SCRIPT OUTPUT
USER
APPLICATION
CONTROL SCRIPTS
SEND COMMANDS
RETRIEVE DATA
WEB BROWSER
CUSTOM SCRIPT-BASED
WEBPAGES
HOST
EM405
-
8
RUN
-
TIME ENVIRONMENT
EMBEDDED ON EM405-8
ARM PROCESSOR
STANDARD TOOLS
TELNET –RAW SOCKET I/F
TERMINAL EMULATOR
TEXT-BASED DEVELOPMENT
ETHERNET
COMMANDS
AND DATA

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1.1 PURPOSE OF EQUIPMENT
The EM405-8 was designed for measurement, automation and control applications. The EM405
easily interfaces a VITA 12-1996 standard M-Module to a typical Ethernet network. The carrier
allows the numerous functions available in the M-Module mezzanine format to be remotely
located near the unit-under-test, easing many system integration issues. Over 100 M-Modules
are available from numerous manufacturers.
The scripting utilities were added to the EM405-8 to allow users to fully utilize the embedded
processor of the EM405-8 and to allow for easy customization of the integrated unit.
1.2 THE LUA SCRIPTING LANGUAGE
Lua (pronounced LOO-ah) is a powerful, fast, lightweight embeddable scripting language. It is
important to note that the name Lua is not an acronym. Lua was written in ANSI-C and is
designed to easily integrate with other software written in C and other conventional
programming languages. Thus,one of Lua’s primary strengths is its extensibility. Lua’s
extensibility is two-fold. Lua can be used to extend an application by embedding Lua scripting
into the application. Also, Lua itself is extendible allowing Lua scripts to utilize libraries and
components written in other programming languages.
Lua is an interpreted language in that Lua programs are stored as text that is interpreted at run-
time. Inreality, Lua code is compiled atruntime into an intermediate form; however, the fact
that compilation is performed at runtime allows scripts to be run directly from text and allows
Lua to retain the designation of an interpreted language.
Lua is free software distributed under the terms of the MIT license. The MIT license is short and
very liberal, allowing the user unrestricted use the software.
Further details, including documentation and references can be found at www.lua.org.
1.3 KEY FEATURES OF EM405-8 SCRIPTING
The EM405-8 implementation of scripting includes the basics of Lua including all standard
libraries, as well as EM405-8 specific extensions and EM405-8 specific script development
tools. Key features include:

 Lua 5.1 programming language interpreter

 Lua 5.1 standard libraries (math, table, string, i/o, operating system, etc.)

 EM405-8 extensions to control M-modules and EM405-8 utilities

 Call high-level M-module drivers and other libraries

 TCP/IP based interactive interpreter for development

 Develop scripts using any text editor. No compilation required

 Store and retrieve data to/from mass storage device (mass storage is an EM405-8 option)

 Receive commands and pass data over the Ethernet interface

 Network based commands to use and manage scripts (store, retrieve, run, halt, etc.)

 Create custom web pages to control the instrument

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1.4 APPLICABLE REFERENCES
In addition to this reference manual there are several sourcesof further information on both the
EM405-8 and the Lua programming language. These documents should be referenced for details
of topics not covered or not elaborated on by this manual. The most applicable references are:
- EM405-8 User’s Manual, C&H Technologies, Inc., C&H part No: 11029384.
- Programming in Lua – 2nd Edition, Ierusalimschy, Roberto, Rio de Janeiro, 2006
- Lua Reference Manual, Ierusalimschy, Roberto, De Figueiredo Luiz Henrique, Celes
Waldemar, Lua.org, 2006
- Lua.org, http://www.lua.org
- Alien, http://alien.luaforge.net/, http://luaforge.net/projects/alien/

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2.0 USING AND MANAGING SCRIPTS
The scripting utilities are accessible via the standard EM405-8 command interfaces (VXI-11 and
raw socket). In addition, a special scripting socket interface is available to help develop and
debug scripts. A set of use and management commands are defined and any of these commands
can be sent via any ofthe available interfaces with a few exceptions.
2.1 COMMANDS
The scripting commands allow the user to develop, use and manage scripts. These commands
are the primary interface to the scripting utilities and are used during both development and
deployment of scripts. They are available, with a few exceptions, via any of the EM405-8’s
command interfaces including the special scripting socket interface. A complete list of use and
management commands is shown in Table I. Details of each command can be found in the
subsequent sections.
Table IUse and Management Commands
?|help list command help
data <data> send up to 16Kbytes to a script (VXI-11 only)
halt <script> halt the script of the specified name
-l <script> halt last script started of specified name
-nx <script> halt script number x of specified name
-a [script] halt all running scripts
list list all scripts
-l [script] list details (script name optional)
-r [script] list if running (script name optional)
read <script> read the specified script
remove <script> remove the script
retrieve <script><port> retrieve the script using the specified port
-d delete the file upon retrieval
run <script> run specified script
-e <command> execute command
-i enter interactive mode (scripting socket only)
socket? returns 1 if scripting socket running,0 if not
-p returns the port of the scripting socket
upload <script><port> upload the script using the specified port
-x execute script after upload
-o overwrite script if file exists
ver returns versions of Lua and EM405-8 extensions
Note: An asterisk (*) is required before the command if sent via the VXI-11 or raw socket interface. The
EM405-8 contains a binary command protocol. An asterisk (*) character denotes that the remaining
command consists of ASCII characters. If the first byte is anything other that an asterisk (*) the EM405-8
perceives it as a binary command. The binary commands are not available via the scripting socket therefore
the asterisk (*) is not required nor recognized.
2.1.1 ? | Help
The help command or simply ‘?’ will return a list of commands along with argument options
and descriptions similar to Table I. The result will be output via the same interface from which
the command was received.
help or ?