Siemens S7-300/400 (STEP 7) PLC Troubleshooting
Siemens S7-300/400 PLC Troubleshooting

Duration:
3 days

Prerequisites:
To be able to cope with the range of practical troubleshooting exercises & get maximum
benefit from the course, attendees need to have attended the Siemens S7-300/400 Getting
Started course or have a reasonable working knowledge of Siemens S7-300/400 PLCs &
STEP7 software.

Aims:
The Troubleshooting course targets maintenance personnel who need to be able to use the
full STEP7 diagnostic toolkit to effectively troubleshoot S7-300/400 hardware problems &
machine or process faults. The course is entirely practical & consists of troubleshooting a
range of fault scenarios to establish a logical approach to faultfinding & to reinforce the use of
standard tools & test procedures.

Objectives:
For specific course objectives see Training Record Log.

Content:
Logical Approach to Faultfinding 
- Understand what should be happening 
- Understand what is/is not happening 
- Understand the reasons why most faults will not be PLC hardware or software & are much more likely to be due to field device failures or wiring problems 
- Define the symptoms & consider possible causes 
- Perform appropriate checks to localise the problem

Troubleshooting Siemens S7-300/400 hardware problems 
- Know the first level checks to begin to quickly distinguish between PLC & field faults 
- Know typical fault symptoms for common PLC hardware (module) failures 
- Be able to recognise & interpret the meaning of external system diagnostic LEDs 
- Be able to correctly interpret the status of I/O LEDs & relate these to the operation of field
devices to distinguish between I/O module faults & wiring or field faults 
- Know how & where to use a meter to check & confirm I/O module power supplies & for correct operation of digital & analogue I/O circuits 
- Know quick methods to identify a failed I/O module 
- Know the symptoms of using a faulty comms cable or if connected to the wrong CPU comms port

S7-300/400 PLC system Resets & Re-starts 
- Understand the effect on the operation of the PLC (program & memory) of stopping & restarting (PGM to RUN mode) or cycling power 
- Understand how & when to use Memory Reset & understand the effect of this on system
operation 
- Understand how Memory Reset differs when invoked on CPU utilising Micro Memory Card (MMC)

Troubleshooting “simple problems” through interpreting Siemens S7-300/400 program code 
- Review the 3 program display modes (LAD, STL, FBD) & be able to interpret simple code for each 
- Know how to use the Search tools in a program to trace I/O status 
- Recognise & understand the different TMR/CTR formats in STL 
- Know the conditions under which on-screen status is displayed incorrectly 
- Be able to read an S7-300/400 program printout & interpret cross reference information to
trace signals when troubleshooting 
- Know how to interpret status in STL with RLO & accumulator

Diagnostic tools in STEP7 
- Know how to generate on-screen Cross Reference data 
- Know how to compare a program in the PLC with a program on disk & be able to interpret
the report 
- Know how to set up & use the Monitor/Modify Variables display using VAT tables to monitor multiple I/O points & data registers in the S7-300/400 
- Know how to use the Force function with S7-300/400 to set/reset a point or to step-on a
sequence & understand the dangers 
- Know how to use the Diagnostics Buffer facility & how to interpret the information provided
to troubleshoot more difficult problems

Tips & Tricks when Troubleshooting with S7-300/400 
- Know the easy methods to be able to display more STL code in ladder 
- How to unlock some “hidden” code 
- Simple program tools to time or count events, to prove status & trap intermittent faults

Further S7-300/400 troubleshooting practicals 
- Troubleshooting “more complex” problems 
- Troubleshooting S7-300/400 systems with programs held on Flash/MMC memory 
- Troubleshooting data handling problems 
- Troubleshooting problems with analogs 
- Troubleshooting programs which make extensive use of Data Blocks 
- Troubleshooting problems which include Indirect Addressing 
- Introduction to third party diagnostic tools e.g. PLC Analyser pro 5

Highly Recommended Follow-up Courses 
- Siemens S7-300/400 Networked Systems
The benefit of attending this further 3 day course is that delegates will be able to gain knowledge & practical experience of maintaining & troubleshooting Siemens PLC automation control systems that use MPI, Profibus DP & ASi. An introduction to Ethernet will also be given. 
- Understanding S7 Programs
The benefit of attending this further 3 day course is that delegates will be able to gain knowledge & practical experience of modifying or develop routines & applications for Siemens PLC controlled automation control systems.
 
Tools
 
Key Details
Duration3 days
 
£770
per delegate