CMS Pixel PLC Code Review Closing Session

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CMS Pixel PLC Code Review- Closing Session -
Christian Veelken UC Davis 06/26/08
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The revised Pixel PLC Code

• Changes to Pixel PLC Code resulting from Review
• Changes in Functionality
• Coding Improvements
• Improvements to Hardware Configuration
• Lifetime of Relays
• Configuration Parameter Checks
• Open Issues

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Changes in Functionality

• Implemented Diagnostic Interrupt Organization
  Blocks
• OB 80, OB 81, OB 88
• OB 121, OB 122

Stefan Lueders Piero Girgio Verdini

• Added Data-Block for Log-Messages
• filled with Entries whenever one of the
  Diagnostic OBs gets called

Adapted from Example Code provided by Stefan
Lueders
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Coding Improvements - 1

• Reduced number of Function Blocks
• FC 1110 isEven replaced by MOD 2
• merged FC 1400 and FC 1401
• merged FC 1411 and FC 1412
• removed FC 1421 testBit

Jim Kowalkowski Kevin Krause Stefan Lueders

• Replaced all Instances of Time_of_Day by
  Date_and_Time Variables Date_and_Time now
  consistently used everywhere in the Code

Jim Kowalkowski

• FC 1240 syncSystemDate_and_Time removed
• replaced by Timer Server

Stefan Lueders Piero Girgio Verdini
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Coding Improvements - 2

• Return codes of SFC 20 BLKMOV and SFC 21 FILL
  taken into account everywhere in the Code

Jim Kowalkowski Kevin Krause Stefan Lueders Piero
Girgio Verdini

• Changed Order by which Functions are compiled in
  Makefile, taking into account Dependencies

Stefan Lueders

• Shortened Variable Names
• ? No Warnings during Compilation anymore

Stefan Lueders Piero Girgio Verdini
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Coding Improvements - 3

• Added Checks for
• lower Alarm Threshold lt upper Alarm Threshold
• to FC 110 and FC 111

Stefan Lueders Piero Girgio Verdini

• Changed Heart-Beat Period from 1.6s to 2min
• ? will come back to this later

Stefan Lueders Piero Girgio Verdini

• Other (minor) Code Improvements
• (Details of which sent to respective
  Reviewer)

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Improvements to the HW-Config.

• Added IP Address Protection

Stefan Lueders

• Added Password Protection for read/write Access
  to PLC via Siemens Step7 software

Stefan Lueders

• Enabled Diagnostic Interrupts

Stefan Lueders Piero Girgio Verdini
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Lifetime of Relays

• Relay specified for 1 million Switching Cycles _at_
  0.5 A, 24V DC
• actually lower Limit, as current significantly
  smaller in Pixel case
• Relay might break after 2-3 weeks of operation
  in case Heart-
• Beat Signal has Period of 1.6s.
• ? Change Heart-Beat period to 2 minutes
• ? Lifetime Expectancy for Relay increased to 3-4
  years minimum.

Stefan Lueders Piero Girgio Verdini
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Configuration Parameter Checks - 1

• Stefan Lueders suggested to move the
  Implementation of Validity Checks performed on
  the Configuration Parameters uploaded by PVSS
  from the Pixel PLC Code to PVSS
• Decided not to to it
• Reasons

• The Change would not reduce the overall Amount
  of Code
• (just move it from the PLC to PVSS, where it
  will not be
• significantly easier to maintain, we
  believe).
• The PLC code would become simpler, but at the
  same Time the
• PVSS code would become more complex.

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Configuration Parameter Checks - 2

• We do actually prefer to perform the Checks in
  the PLC,
• so that the entire Chain of Data Transmission
  can be validated
• (Concerns about possible Data Corruption by
  the PVSS native S7
• Driver have been raised by Piero Giorgio
  Verdini)
• The current Implementation of the Configuration
  Parameters in
• the Pixel PLC Code has been tested, debugged
  and verified to
• work.
• The effort to move the Code for the
  Configuration
• Parameter Checks from Pixel PLC code to PVSS
  and repeat the
• Testing, Debugging and Verification of the
  Code would be
• significant.

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Open Issues - 1

• CRC-16 Checksums
• Different Opinions held by different Reviewers
• Stefan Lueders
• I believe this is Overkill
• Piero Giorgio Verdini
• PVSS data transmission - strange things to
  happen
• from Time to Time.
• Packets need to be broken up on large
  Transmissions.
• Sometimes blocks are garbled.
• (Minutes of Meeting 04/25/08)

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Open Issues - 2

• Gennadiy Lukhanin
• It may be useful to store Checksums for DB
  1xx
• in a Data-Base, so that the entire Chain of
  Data
• Transmission from the Data-Base to
  Data-Blocks in the PLC
• can be validated.

• Common Issue of CMS Pixel and Silicon Strip
  Tracker
• PLC Codes

Unit Tests/automated Code Validation All
Reviewers pointed out that this would be good to
have, but suitable Tools are lacking !!

• Issue common to PLC Codes of many (if not all)
• CMS Subdetectors

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Thank you !!
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Special Acknowledgements

• Piero Giorgio Verdini
• for taking the Time to discuss his Comments
• with me
• Stefan Lueders
• for providing me with an example Implementation
  
• of the diagnostic Interrupt Organization Blocks
• and for taking the Time for many useful
  Explanations