create & duplicate alarm subroutines in Siemens S7-200 SMART

When working with Siemens S7-200 SMART PLC, modular programming through subroutines is a key best practice — especially when handling alarm logic. Creating reusable and easily duplicated alarm subroutines allows for scalable project design, efficient troubleshooting, and consistent HMI behavior.

In this guide, we’ll walk you through:

How to create an alarm handling subroutine in Step 7 MicroWin
How to duplicate the subroutine for multiple alarm conditions
How to integrate the logic with HMI alarm indicators
A practical video tutorial you can follow via the official YouTube channel:
🎥 Weblog5me YouTube Channel

📌 What Is a Subroutine in S7-200 SMART?

In Step 7 MicroWin, a subroutine (SUB_xx) is a user-defined block of logic that can be reused multiple times from the main program or other blocks. Each subroutine helps:

Improve code organization
Minimize redundancy
Simplify debugging and testing

For alarms, this means one universal logic block can handle multiple conditions like high temperature, low pressure, motor overloads, etc.

⚙️ Step-by-Step Guide: Creating an Alarm Subroutine

✅ Step 1: Open Step 7 MicroWin Smart

Launch your S7-200 SMART project
Navigate to the Program Blocks section

✅ Step 2: Create a New Subroutine in Siemens S7-200 SMART

Right-click on Subroutines → Add New Subroutine
Name it: ALARM_HANDLER

✅ Step 3: Build Basic Alarm Logic

Inside ALARM_HANDLER, implement the alarm logic, such as:

I0.0: Input condition (e.g., temperature sensor fault)

M0.0: Memory bit to trigger HMI alarm

You can also use SET/RESET coils for latched alarms.

🔁 How to Duplicate Alarm Subroutines

✅ Step 4: Copy the Subroutine Block

Select ALARM_HANDLER → Right-click → Copy
Paste and rename it to ALARM_HANDLER_2, ALARM_HANDLER_3, etc.

Each duplicate can monitor different inputs (e.g., I0.1, I0.2) and write to different memory bits (e.g., M0.1, M0.2).

✅ Step 5: Call Subroutines in Main Program

In the Main OB1, add CALL instructions for each subroutine:

This executes all alarm checks in each PLC cycle.

📲 Link with HMI Alarm System

If you’re using a compatible HMI panel, map the M bits (M0.0, M0.1, etc.) to alarm indicators or pop-ups using:

HMI Tags (Bool)
Trigger → Message text display
Acknowledge → Reset Memory bit if required

🎥 Watch Step-by-Step Video

For full visuals and hands-on tutorial, visit:
🔗 Weblog5me YouTube Channel

The video walks through the real-time subroutine creation, duplication, and HMI configuration from scratch using Step 7 MicroWin SMART.

🌐 Expand Your PLC Toolkit with Downloads

Get downloadable tools, firmware, and software at:
🛠️ vohauipr.com – Your source for Siemens, Rockwell, and automation resources.

Suggested download:
➡️ Step 7 MicroWin SMART Trial Package

By mastering how to create and duplicate alarm subroutines in the S7-200 SMART PLC using Step 7 MicroWin, you can build reliable and scalable control systems that are easy to debug and integrate with HMI alarms. This method boosts programming efficiency and ensures consistent alarm handling across all your automation projects.

To take your PLC projects to the next level, explore downloadable tools and software packages from vohauipr.com—a trusted resource hub for industrial automation.

Here are 5 useful downloadable products to support your development:

How to Create and Duplicate Alarm Subroutines in S7-200 SMART Using Step 7 MicroWin | HMI Alarm

📌 What Is a Subroutine in S7-200 SMART?