This document provides instructions for programming a PLC using Siemens Step 7 Micro/WIN software. It describes the following key steps: 1. Opening the Micro/WIN software and creating a new project. 2. Writing a simple ladder logic program with a timer, comparator, and outputs. 3. Downloading the program to the PLC and placing the PLC in run mode to execute the code.

1. PLC Programming
GRESHA S. SAMARAKKODY

2. Step 7 – MICRO/WIN
This software makes programming of S7-200 easier.
• Basic instructions:
INPUTS will be defined as IX.X
OUTPUTS will be defines as QX.X
FLAGS will be defined as MX.X
Example :
I0.1 first module’s 1st input
Q0.1 first module’s 1st output

3. Step 1: How to open Step 7 – Micro/WIN
To open the software :

4. Step 7 Micro/WIN Start Window

5. Steps of Running Code on PLC
Open Step
Micro/WIN
Write a Simple
Code in Ladder
Network
Compile Your
Code
Download
Your Code to
PLC
Run PLC to
Perform Code

6. Timers
Table 1 : Timer Numbers and Resolutions

7. Timers
Table 2 : Operations of the Timer Instructions

8. Step 2: Writing a simple program
 Click on “Bit Logic” icon to open bit logic
commands
 Choose “Normally close contact”
Drag and drop the contact to network 1
 Write the M0.0 instead of the question marks (???)
over the contact. M0.0 is a flag contact
 Press the enter button to finish contact definition.

9. Setting up a timer
 Click on “timer” icon to see all timer commands
 Choose TON (on delay timer)
 Drag and drop the TON to network 1 next to M0.0
 Write the T33 instead of the question marks (???) over
the timer box
 Press enter the cursor will go to PT section
 Enter timer setting as : 100
 Press enter to finish setting up the timer

11. Step 3:
Turning the Output On (Network 2)
When the timer value for T33 is greater than or equal
to 40 (40 times 10 milliseconds or 0.4 seconds), the
contact provides power flow to turn on output Q0.0
of the S7-200.

12. Double click the compare icon to display the compare instructions.
Select the >=I instruction
 Hold down the left mouse button and drag the compare
instruction onto the second network
Click on the “???” above the contact and enter the address for the
timer value : T33
 Press the Return key to enter the timer number and to move the
focus to the other value to be compared with the timer value
 Enter the following value to be compared with the timer value : 40
 Press the return key to enter the value.

13. To enter the instruction for turning on
output Q0.0
 Double click the Bit Logic icon to display the bit logic
instructions and select the output coil
 Hold down the left mouse button and drag the coil
onto the second network
Click on the “???” above the coil and enter the
following address: Q0.0
Press the return key to enter the address for the coil

15. Step 4: Resetting the Timer
When the timer reaches the preset value (100) and
turns the timer bit on, the contact for T33 turns on.
Power flow from this contact turns on the M0.0
memory location. Because the timer is enabled by a
Normally Closed contact for M0.0, changing the
state of M0.0 from off (0) to on (1) resets the timer.

16. To enter the contact for the timer bit of T33
 Select the Normally Open contact from the bit logic
instructions
 Hold down the left mouse button and drag the contact
onto the third network
 Click on the “???” above the contact and enter the
address of the timer bit: 33
 Press the Return key to enter the address for the contact

17. To enter the coil for turning on M0.0:
 Select the output coil from the bit logic instructions
 Hold down the left mouse button and drag the
output coil onto the third network
 Double-click the “???” above the coil and enter the
following address: M0.0
 Press the Return key to enter the address for the coil
Save the project File Save As

18. Step 7 Micro/WIN Resetting the Timer
Network 3

19. Whole Example and Output Timing
Diagram

20. Step 5 : Downloading the Sample Program
to PLC
 Click the Download icon on the toolbar or select the
File > Download menu command to download the
program
 Click OK on opened window to download the
elements of the program to the S7-200

21. Upload and Download Button

22. Step 6 : Running the PLC
For STEP 7- Micro/WIN to place the S7-200 CPU in
RUN mode, the mode switch of the S7-200 must be
set to TERM or RUN. When you place the S7-200
executes the program:
Click the RUN icon on the toolbar select the PLC > RUN
menu command
 Click OK to change the operating mode of the S7-200

23. Run and Stop Buttons

24. Counters

26. Operations of the Counter Instructions

27. END