Onboard Plc; Onboard Plc And Syptlite; Benefits; Limitations - Emerson Digitax ST User Manual

Safety Product Mechanical
Information information installation
10

Onboard PLC

10.1

Onboard PLC and SYPTLite

The Digitax ST has the ability to store and execute a 4KB Onboard PLC
ladder logic program without the need for additional hardware.
The ladder logic program is written using SYPTLite, a Windows™ based
ladder diagram editor allowing the development of programs for
execution in Digitax ST.
SYPTLite is designed to be easy to use and to make program
development as simple as possible. The features provided are a sub-set
of those in the SYPT program editor. SYPTLite programs are developed
using ladder logic, a graphical language widely used to program PLCs
(IEC61131-3). SYPTLite allows the user to "draw" a ladder diagram
representing a program.
SYPTLite provides a complete environment for the development of
ladder diagrams. Ladder diagrams can be created, compiled into user
programs and downloaded to a Digitax ST for execution, via the RJ45
serial communications port on the front of the drive. The run-time
operation of the compiled ladder diagram on the target can also be
monitored using SYPTLite and facilities are provided to interact with the
program on the target by setting new values for target parameters.
SYPTLite is available on the CD which is supplied with the drive.
10.2

Benefits

The combination of the Onboard PLC and SYPTLite, means that Digitax
ST can replace nano and some micro PLCs in many applications. The
Onboard PLC programs can consist of up to a maximum of 50 ladder
logic rungs (up to 7 function blocks and 10 contacts per rung). The
Onboard PLC program can also be transferred to and from a
SMARTCARD for backup or quick commissioning / start-up
In addition to the basic ladder symbols, SYPTLite contains a sub-set of
the function from the full version of SYPT. These include,
• Arithmetic blocks
• Comparison blocks
• Timers
• Counters
• Multiplexers
• Latches
• Bit manipulation
Typical applications for the Onboard PLC include,
• Interlocking logic
• Sequences routines
• Custom control words.
10.3

Limitations

The Onboard PLC program has the following limitations:
• The maximum program size is 4032 bytes including header and
optional source code.
• The Digitax ST is rated for 100 program downloads. This limitation is
imposed by the flash memory used to store the program within the
drive.
• The user cannot create user variables. The user is only able to
manipulate the drive parameter set.
• The program cannot be downloaded or monitored over CTNet. The
program is only accessible via the drives RJ45 serial
communications port.
• There are no real-time tasks, i.e. the scheduling rate of the program
cannot be guaranteed. SM-Applications tasks such as Clock, Event,
Pos0 or Speed are not available. The Onboard PLC should not be
used for time-critical applications.
Digitax ST User Guide
Issue: 3
Electrical Getting Basic
installation started parameters
www.controltechniques.com
Running the SMARTCARD
Optimization
motor Operation
• The program runs at a low priority. The Digitax ST provides a single
background task in which to run a ladder diagram. The drive is
prioritised to perform its major functions first, e.g. motor control, and
will use any remaining processing time to execute the ladder
diagram as a background activity. As the drive's processor becomes
more heavily loaded, less time is spent executing the program.

Figure 10-1 Digitax ST Onboard PLC program scheduling

Major drive
functions
User
program
0
The user program is scheduled for a short period approximately once
every 64ms. The time for which the program is scheduled will vary
between 0.2ms and 2ms depending on the loading of the drive's
processor.
When scheduled, several scans of the user program may be performed.
Some scans may execute in microseconds. However, when the main
drive functions are scheduled there will be a pause in the execution of
the program causing some scans to take many milliseconds. SYPTLite
displays the average execution time calculated over the last 10 scans of
the user program.
10.4

Getting started

SYPTLite can be found on the CD which is supplied with the drive.
SYPTLite system requirements
• Windows 2000/XP/Vista. Windows 95/98/98SE/Me/NT4 are not
supported
• Pentium III 500MHz or better recommended
• 128MB RAM
• Minimum of 800x600 shield resolution. 1024x768 is recommended
• Adobe Acrobat 5.10 or later (for viewing User Guides)
• Microsoft Internet Explorer V5.0 or later
• RS232 to RS485, RJ45 communications lead to connect the PC to a
Digitax ST
• Administrator rights under Windows NT/2000/XP/Vista are required
to install the software
To install SYPTLite, insert the CD and the auto-run facility should start
up the front-end shield, from which SYPTLite can be selected.
See the SYPTLite help file for more information regarding using
SYPTLite, creating ladder diagrams and the available function blocks.
Onboard Advanced Technical
Diagnostics
PLC parameters Data
64
UL listing
information
128
Time
(milliseconds)
77