Editing SINUMERIK 828D PLC Code: On-Screen and External Tools

Overview

The SINUMERIK 828D CNC integrates a SIMATIC S7-200 compatible PLC directly inside the controller. This integrated PLC handles all machine-level I/O: spindle enable, axis enable, tool changer, coolant, safety circuits, feed hold, and M/H/T auxiliary functions. The user program is a ladder logic project stored on the CompactFlash card of the PPU (Panel Processing Unit) and is loaded at boot.

Two parallel paths exist for editing that user program:

• On the HMI using the SINUMERIK Operate Ladder Add-On Tool, also referred to as PLC LADDER ON. The tool is an OEM-loaded option that exposes the live PLC on the operator panel and lets you change coil/register values from the keyboard.
• On a Windows PG/PC using Programming Tool PLC828 (sometimes listed as PLC-Programming-Tool 828D). The tool is part of the SINUMERIK Toolbox CD and connects over Ethernet to the controller's X130 service interface or to a company network port.

The integrated PLC of the 828D is documented by Siemens as a SIMATIC S7-200 subsystem. It is not programmable in TIA Portal — TIA targets S7-1200/S7-1500. Always use the S7-200-compatible editor shipped with the 828D. Reference: SINUMERIK 828D Grinding — Editing the PLC user program (ID 109994219).

Prerequisites

Integrated PLC Architecture of the 828D

The 828D PLC is implemented as a SIMATIC S7-200 CPU with a fixed address layout. The user-relevant memory areas are:

The user program is split into OB1 (main cyclic), SBR (subroutines) and INT (interrupt routines) — identical to the S7-200 toolchain. The PLC runs cyclically at the OB1 scan rate and is started by the NC kernel in coordinated mode.

Method 1 — Editing PLC on the HMI (Ladder Add-On Tool)

This is the fastest path when the controller is in front of you and the Ladder Add-On license is present. It is also the only path that does not require an external PG/PC. The tool exposes two functions: online monitoring of the rung with live signal state, and direct editing of selected variables (inputs, outputs, markers, DB words and DB bits) from a STATUS list.

Step 1 — Verify the Ladder Add-On Tool is installed

1. Power on the 828D and wait for the SINUMERIK Operate main screen.
2. Press Menu Select → Commissioning → enter password 1111 (Manufacturer).
3. Press Menu Select → Diagnostics → System → Version.
4. Scroll the installed options list. Look for the entry PLC LADDER ON or Ladder Add-On Tool. If the entry exists, the license is present and active. If the entry is missing, the option is not installed and the only on-screen action you can do is read-only STATUS.

Step 2 — Open the PLC LADDER ON tool

1. From the main HMI screen press SETUP (or the Setup softkey depending on Operate version).
2. Press the PLC softkey. The PLC LADDER ON window opens.
3. The default view is the live ladder. Use the page keys or the mouse wheel to scroll. Signal states are color-coded: green = TRUE, grey = FALSE, blue = forced.

Step 3 — Open the STATUS LIST

1. Press the STATUS LIST softkey.
2. Press the SET ADDRESS softkey.
3. Select the address type: I, Q, M, DB or SM from the dropdown.
4. Enter the address in the value field. Format examples:
   • Bit: I0.0, Q7.3, M100.5, DB10.DBX0.0
   • Byte/Word/DWord: DB20.DBB0, DB20.DBW10, DB20.DBD100
   • Integer/Real: DB30.DBW40 (INT), DB50.DBD80 (REAL)
5. Press ACCEPT. The cursor jumps to the specified address row in the STATUS LIST and shows the current value, format (BOOL, HEX, BIN, DEC, FLOAT) and the read/write permission.

Step 4 — Modify a value

1. With the cursor on the desired row, press the CHANGE softkey. The RW (Read/Write) field becomes editable.
2. Type the new value. For BOOL enter 0 or 1. For BYTE enter 0–255. For WORD enter 0–65535. For DWORD/REAL enter the full decimal or real value.
3. Press ACCEPT. The new value is written immediately to the live PLC.
4. For bit-level writes, the change toggles the operand; the same change is reflected in the active rung in the LADDER view within one OB1 scan.

Step 5 — Save and exit

Press BACK or the area-change softkey to leave the PLC LADDER ON tool. The write is not saved to the CF card automatically; it lives only in the volatile S7-200 image. Treat the HMI STATUS LIST as a debugging surface, not a project editor.

Method 2 — Editing with Programming Tool PLC828 (External PG/PC)

For real code changes — adding a rung, modifying a timer preset, restructuring logic — you must edit the project on a Windows PC. The Siemens-supplied tool is Programming Tool PLC828 (PT 828D). It is a SIMATIC S7-200 compatible editor that communicates with the integrated PLC over Ethernet.

Step 1 — Install the software

1. Locate the SINUMERIK 828D Toolbox CD that shipped with the system. The root folder contains: Programming Tool PLC828, PLC Basic Program, Add On Tools, Configuration.
2. Run the installer for Programming Tool PLC828. Required components: .NET 2.0/3.5, the S7-200 communication DLL, the Microsoft Access runtime used for symbol tables.
3. Accept the default install path (typically C:\Siemens\S7-200\Programming Tool PLC828).
4. If a license key was provided on a USB stick, plug it in and run the AuthorW.exe license manager once.

Step 2 — Establish the Ethernet connection

The 828D PPU exposes two relevant Ethernet ports: X130 (the company/service network, default IP 192.168.214.1) and on the operator panel front a service / X127 port (default IP 192.168.215.1). Either is suitable for PLC programming.

1. Set the PG/PC Ethernet adapter to a static address in the same subnet:
   • For X130: 192.168.214.100, mask 255.255.255.0
   • For X127: 192.168.215.100, mask 255.255.255.0
2. Plug a patch cable from the PG into the chosen PPU port. Direct PG↔PPU requires a crossover-capable adapter or a modern auto-MDIX port — both 828D ports are auto-MDIX, so a straight cable works.
3. Verify the link with ping 192.168.214.1 (or 192.168.215.1). A reply confirms the TCP path is up.

Step 3 — Open the project and go online

1. Launch Programming Tool PLC828.
2. Click File → Open and load the matching *.S7P project file. If you do not have the source, click PLC → Upload Station to PG to read the live program out of the controller and save it locally as a new project.
3. Click PLC → Communications → set the remote address (e.g. 192.168.214.1) and select TCP/IP.
4. Click Connect. The tool reads the PLC type (S7-200), firmware version and the user program size. A green status bar at the bottom confirms the link.

Step 4 — Make the change and download

1. Open the relevant program block (OB1, SBR0, SBR1, …) by double-clicking it in the project tree.
2. Edit the rung: insert contacts, coils, timers, comparators, math blocks. The toolset matches STEP 7 Micro/WIN: drag from the instruction tree on the left, drop into the network editor.
3. Compile with PLC → Compile. Errors are reported in the Output window; the program is not downloaded until compile is clean.
4. Click PLC → Download. Confirm the warning dialog. The tool will first stop the PLC, write the new program, then restart it. Expect a brief drop in I/O — the 828D's NC remains running but machine outputs go to safe state for 1–2 scan cycles.
5. Save the modified project to the PG/PC with File → Save As to a versioned path.

Step 5 — Archive the new project to the CF card

1. From SINUMERIK Operate press Menu Select → Commissioning → PLC → PLC Archiving.
2. Insert a USB stick formatted FAT32 with enough free space (≥ 64 MB recommended).
3. Select Series commissioning → Create archive. The tool writes both the current PLC project and the basic program to a date-stamped folder.
4. After download, do a full series commissioning archive to ensure the modified PLC is the one written to the next commissioning backup.

Method 3 — Direct CF Card Editing (Offline)

For service emergencies where no PC or HMI tool is available, the PLC project can be edited off the CF card on a Windows PC. The card image contains the project at card\plc\proj.s7p (older builds) or in a hashed path under card\oem\sinumerik\hmis\plc\ on newer SW 4.7+ systems.

1. Power down the 828D and remove the CF card from the PPU.
2. Insert the CF into a Windows reader.
3. Make a full .img of the card using Win32 Disk Imager or HDD Raw Copy. This is the safety net.
4. Copy the project file out, edit with PT PLC828, copy back, and verify the SHA256 of every file in the modified card.
5. Re-seat the card and boot. The PLC loads the modified project.

Connection Path Decision Matrix

Verification Procedure

After any PLC edit, run the following verification sequence before returning the machine to production:

1. Compile clean: PT PLC828 reports zero errors and zero warnings in the Output window.
2. Online compare: PLC → Compare → PG vs PLC must show identical rungs. Any difference means the download did not complete.
3. First scan: SM0.1 (first-cycle flag) must pulse for one OB1 cycle. Observe via STATUS LIST: SM0.1 reads 1 for ~30 ms after restart.
4. Watchdog clear: SM0.6 (alternating flag) toggles every scan; if it stops, the PLC has entered STOP. Check PLC status LED on the PPU — solid red = STOP, flashing = fault, off = RUN.
5. I/O scan: toggle a known input (e.g. cycle start) on the operator panel and verify the matching M or DB bit changes via STATUS LIST or PT PLC828 status chart.
6. NC handshake: with the machine in JOG, vary the feed-rate override potentiometer and watch DB10 (NCK signals) — the override word must track within 100 ms.
7. Sign-off archive: create a Series commissioning archive and store on a labelled USB stick tied to the machine's serial number.

Troubleshooting Matrix

Safety and Access-Level Reminders

• Siemens documents the integrated PLC as part of the basic program. The basic program is supplied by the OEM and is normally write-protected. User modifications should target user SBRs, not the basic program OB100 / OB1 segments.
• Modifying safety-relevant logic (Emergency Stop chain, axis safe-stop, guard interlock) is the responsibility of the OEM. The 828D's integrated PLC is not a safety PLC (no SIL/PLe capability). For functional safety use a separate SIRIUS 3SK safety relay or a SIMATIC F-CPU coupled through PROFIsafe.
• Always log changes: maintain a written PLC_Change_Log.xlsx with date, machine serial, software version, change description, and engineer signature. This is required for CE re-assessment under ISO 13849-1 and for FDA 21 CFR Part 11 regulated environments.

Frequently Asked Questions