Foxmere Technologies

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S5-135 / S5-155 PLC Level 1


Course Outline

Upon completion of the course the student should:

  • Be able to recognise S5 hardware and be able to replace modules when a fault occurs.
  • Be able to operate the S5 software to make it perform certain tasks.
  • Understand basic S5 instruction set and be able to make minor modifications to software.
  • Be able to backup and restore a PLC program when required.
  • Be able to perform basic system diagnostics when a problem occurs.

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Equipment per Delegate

  • Siemens S5-135 / S5-155 PLC.*
  • PC or laptop.
  • Simulator.*

* Per two delegates. This is the only course we run where delegates share equipment.

Course Content

To fault find a system you need to know exactly how it works.

How exactly does a PLC work?

  • Am I getting the input to the PLC?
  • The LED on the output card means I am getting voltage out right?
  • What exactly happens in-between? Theres more than just a program in the CPU.
  • How exactly IO scan the program?
  • What is this Watchdog Timer? Is it that important?
  • Can I use the same output twice? That's bad programming isn't it?
  • A PLC is a logic controller, so use a logical approach to fault find it.
  • What are the 8 simple test points to check?
  • What is the difference between forcing and toggling?

How do I do the following?

  • How do I check power is on and the PLC is in the right mode (RUN or Program).
  • Check for a fault condition.
  • Establish a link to the PLC (project settings).
  • If comms problem check PG/PC interface.
  • Create a blank project and take a backup.
  • Open project for PLC and go online.
  • Interrogate I Stack and B stack.
  • Identify hardware / software faults.
  • Change the battery.
  • Change modules if necessary (with and without spares).
  • Identify a PLC / comms fault.
  • Check all settings against a template, etc.
  • Check hardware.
  • Clear memory and download program.
  • Check software against latest copy (Compare function).
  • Monitor program.
  • Searching for specific operands and instructions.
  • Changing timer, counter values online.
  • Making minor modifications online and offline.
  • Check or create a status table to establish parameter status.
  • Force a parameter if required.
  • Use Xreference to assist with software diagnostics.
  • Upload and download project.
  • Display documentation (symbols, comments).
  • Reassign an IO address and change software addresses (Rewire Function).
  • Printing cross reference / program listings, etc.

Background information also covered.

Understanding the following

  • Introduction to MS-DOS
  • Siemens DOS Files (ST.S5D, PX.INI) etc
  • Number formats, bits, bytes, words, double words
  • Binary, HEX, octal, floating point, integer.
  • Data types and parameter types, bool, etc.
  • IO addressing.
  • Block types.
  • Program structure
  • Variable types (local and global).
  • How to monitor various blocks (OB, PB, FB, DB (FBs in particular).
  • Ladder, STL, FBD programs
  • Basic instructions, contacts, set, reset, etc.
  • Timers and counters.
  • Comparators, maths.
  • How to make minor modifications.
  • Altering values in a status variable table.
  • Back-tracking through a program to establish where power flow stops.
  • Overall reset procedure.
  • Fault finding tips.


Provisional bookings can be made via email, phone or letter. Confirmation in writing with a purchase order number is required four weeks prior to the course start date.

Dates may be offered to other customers after this date.

Joining instructions are sent out approximately two weeks prior to the course start date.

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Course Times

Typical course times are 09:00 to 16:30. Alternative arrangements can be made for customised and on-site courses.


A light lunch will be provided when training at our in-house facility.

Payment and Cancellations

Fees are based upon payment being made to confirm course booking. Should you be unable to meet these terms please advise us as we will be able to re-quote on your payment terms.

Prices are quoted exclusive of VAT. New Customers are required to pay pro forma.

Requests for cancellation must be made via email or letter. Cancellation charges may apply.

Course Specifics


Siemens S5-135 / S5-155


MS-DOS based S5


5 days

Max. Delegates



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