Siemens TIA Portal (STEP 7)

TIA Portal (Totally Integrated Automation Portal) is Siemens' engineering software. STEP 7 inside it programs SIMATIC S7-1200 and S7-1500 PLCs, and the same project can contain HMI screens (WinCC), drives (Startdrive) and safety.

STEP 7 Basic vs Professional

Older S7-300/400 projects may still be in STEP 7 V5.x (SIMATIC Manager), which looks completely different. Small LOGO! modules use LOGO! Soft Comfort. A 21-day trial license is available for TIA Portal.

How a project is organised

• Devices & networks: drag the CPU and I/O modules in, set IP addresses and the PROFINET network.
• PLC tags: the symbol table. Every address gets a name: %I0.0 = "Start_PB".
• Program blocks:
  • OB (organisation blocks): called by the operating system. OB1 "Main" runs every scan; cyclic interrupt OBs run at fixed intervals; startup OB100 runs once.
  • FC (functions): code without memory.
  • FB (function blocks): code with memory stored in an instance DB, e.g. one FB "Motor" used for every motor.
  • DB (data blocks): global data, recipes, setpoints.
• Watch and force tables: monitor and change values while online.

Languages

LAD (ladder), FBD, SCL (structured text), STL (statement list, S7-1500/300/400 only) and GRAPH (sequences). See PLC programming languages.

Addressing

Inputs %I0.0, outputs %Q0.0, memory %M0.0, using byte.bit numbering (see PLC addressing). On S7-1200/1500, data blocks are "optimized" by default and accessed only by name, e.g. "Recipe".Speed. Timers and counters are IEC instructions (TON, TOF, CTU) with their own instance data.

Typical workflow

1. Create a project, add the CPU (or upload the hardware from a connected PLC).
2. Define tags, write OB1 and your FBs/FCs.
3. Compile and fix errors.
4. Test with S7-PLCSIM (simulated CPU on the PC), or connect to the real PLC over Ethernet.
5. Download to the device, set the CPU to RUN.
6. Monitor (the glasses icon): live power flow in the blocks, watch tables, and trace for fast signals.

Tips

• Comment every network and tag; TIA Portal shows comments in monitoring.
• Use FBs with instance DBs for repeated equipment (motors, valves).
• Use the cross-reference (F11) to find where a tag is written; a tag written in two places is a classic bug.
• Archive projects (.zap) to keep a compact backup.

Practise Siemens-style addressing (I0.0 / Q0.0 / M0.0) for free in the PLC Sim Lab Playground.