Table of Contents
- What is an MSP driver?
- Where are the drivers after installation?
- Where can I find the notes files after drivers are
installed?
- After Configuring an SP2000/4000 there is no
communications with the PLC?
- What is MSP update time?
- How many MSPs can be used on a single PLC?
1. What Is an MSP Driver?
An MSP driver is a small ladder logic program that is added to the
user program. All code is standard ladder logic. When possible it is written as one to
three subroutines. The subroutine is preferably called either as a time interrupt.
In some models the logic in the main program fixed and the subroutines are called
from the main program.
The user can import the driver ladder logic into their program or
they can start with our driver and build their program from it. All available
drivers have been fully test and optimized for the target PLC
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2. Where are the drivers after installation?
After installation if the default paths are used the drivers are in a folder
labeled "C:\MSP\DRIVERS". In this folder is another folder for each PLC
brand. In each PLC brand folder are folders for the model of that brand being used.
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3. Where can I find the notes files after
drivers are installed?
After installation if the default paths are used the drivers are in a folder
labeled "C:\MSP\DRIVERS". In this folder is another folder for each PLC
brand. In each PLC brand folder is a file named "Notes.doc". This
file is a Microsoft word file this is suitable for printing. The three main parts of
this file are also on the web site as web pages under the Notes, Wiring Diagrams, and Memory menus. The Microsoft Word
version is also available for download in any of these sections.
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4. After Configuring an SP2000/4000 there is no
communications with the PLC?
After configuration of the SP2000/4000 the configuration cable must be removed
and power cycled. The SP2000/4000 can only be in one mode at a time. It is
either in configuration mode or run mode. The configuration cable short one of the
pins on the SP connector to ground. This pin is only examined on power up.
To Change to Run Mode remove the configuration cable from the
SP2000/4000 and disconnect power to the board for 10 seconds. When the unit is now
powered up it will be in run mode.
To Change to Program Mode plug the configuration cable into the
SP2000/4000 and disconnect power to the board for 10 seconds. When the unit is now
powered up it will be in program mode.
Note that the MSC and MSP families do not have this limitation. They can
be connected to the configurator and be on line at the same time.
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5. What is MSP update time?
MSP update time is a function of the scan time. To transmit the entire
analog value with the default settings takes 58 scans. If the scan time is set for
10 msec then the update time is 580 msec or 0.58 seconds.
Many options exist to speed up the update time. If scan time is reduced to
5 msec which is supported by many PLCs then the update time is 0.29 seconds. Often
the entire 16 bit resolution is not necessary and only 10 bits are required. In this
case the entire value takes only 40 scans and even with a scan time of 10 msec the update
time is 400 msec or 0.4 seconds.
A standard feature name "Delta Mode" sends only the change from
the last transmission. By default the delta value is 4 bits which take 22 scans to
transmit. At 10 msec the delta update is 220 msec or 0.22 seconds. Any time
the delta is larger than a 4 bit number the entire value is transmitted. By default
the entire value is transmitted after every 16 delta. The frequency of complete
updates and size of the delta are user adjustable allowing the best fit for the
application. Note that setting the delta updates to zero forces the entire value to
be transmitted every time and effectively turns off the delta update.
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6. How many MSPs can be used on a single PLC?
As many MSPs can be used on a single PLC as there are discrete inputs and
outputs.
On many PLCs when the total number of channels exceeds 2 or 3 or 4 the scan time
must be increased. The effect of total number of channels on scan time varies
greatly depending on the brand and model of PLC. The scan time can always be slowed
down enough to accommodate the desired number of channels.
When adjusting the scan time the requirements of the process must be considered.
In any application with a large number of analog inputs and outputs, probably a
small number are going to be more important than the majority and require faster updates.
This can easily be accomplished by setting a fast scan time in the PLC and the
important MSPs and processing them every scan. The other MSPs can be set at a lower
value and their processing evenly distributed over several of the faster scans. This
minimizes the number of MSPs processed in a single scan.
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