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For machines with Heidenhain TNC and iTNC controllers this program enables to read and output PLC (Programmable Logic Controller) data from an external PC connected to the controller via Ethernet network.

It supports reading of PLC MARKER, BYTE, WORD and DWORD values. For all supported data types it allows you to scan adjustable PLC address ranges and output their values. You can also search PLC address ranges for a target value. It automatically converts output data from older TNC devices like TNC 426 and 430 to match the values shown at the controller.

  • Note: This program does NOT require Heidenhain Option 18 (DNC).



  • Make sure that you have an Ethernet network connection between your PC and the machine and get data, use our HeidenhainData utility to do so.
  • In case you use a firewall at your PC or your company network please make sure that there is an exception in both directions for the TCP Port the controller uses for communication (default 19000). You can use our tool Device Port Scanner to check if your controller is reachable via this port.



Download and extract HeidenhainPLC.exe to a folder of your choice on your PC.

  • Double click HeidenhainPLC and enter the IP Address or DNS Hostname of your controller (1).
  • If required, enter the PLC Password or code number of your controller (2).
  • Click on button [Connect] (3), if successful the name of the button changes to ‘Disconnect’.
  • Select the desired PLC area, here DWord, initially Marker is selected (4).
  • Input a start (5) and end (6) address for the PLC address range you’d like to get data from.
  • After clicking button [Query] (7) the program tries to read the requested data.

Read Heidenhain TNC PLC Data

FIG 1:    Read Heidenhain TNC PLC Data

If successful, the program outputs the PLC data in the area at the right (8) in form of PLC area (PLC Marker, PLC Byte, PLC Word or PLC DWord) + address: output value.

  • Note: If you search for a Word address value the start address has to be divisible by 2 e.g. 490, 492.
    For a DWord address value the start address has to be divisible by 4 e.g. 360, 364.

To search for a target value in the selected address range enter Target Value and check ‘Search Target Value’ before clicking button [Query].

If searching for markers by target value only 0 or 1 as target value deliver results.

  • Note: For security reasons the searchable address range is automatically limited by the program (50 for Markers and Bytes, 100 for Words and 200 for DWords).


If you have installed CNCnetPDM on your PC with a license other than a ‘free license’ and run this program from the folder where CNCnetPDM is installed you get unlimited functionality and output. With a free license you can search for values of one address at a time. Searching for target values is not supported in this case. Please see licensing for details or contact us if you have any questions.

  • Note: If you like to run this program from a different location on your PC you can simply copy your CNCnetPDM.ini file to this directory.


Here are some useful PLC addresses for Heidenhain iTNC 530, TNC 426 or 430 devices:

Heidenhain TNC PLC DWORD Table

FIG 2:    Heidenhain TNC PLC DWORD Table

MARKER 4150: OP Mode Manual
MARKER 4152: OP Mode MDI
MARKER 4151: OP Mode Hand wheel
MARKER 4153: OP Mode Automatic single
MARKER 4154: OP Mode Automatic full
MARKER 4155: OP Mode Traversing
MARKER 4176: PR Mode Running
MARKER 4175: PR Mode Interrupted
MARKER 4177: PR Mode Error active
MARKER 4220: PR Mode Stopped extern
MARKER 4221: PR Mode Stopped intern
MARKER 4178: PR Mode Emergency A
MARKER 4222: PR Mode Emergency B
MARKER 4582: PR Mode Emergency C
MARKER 4170: PR Mode Finished

WORD 492: Override (% to be divided by 100)
WORD 272: Execution mode (subtract 1 to get real mode)
WORD 320: Target speed
WORD 322: Actual speed

DWORD 356: Programmed speed
DWORD 364: Target speed
DWORD 368: Actual speed
DWORD 360: Programmed feed rate
DWORD 388: Actual feed rate


  • If HeidenhainPLC connects to your controller but you get blank output please check if ‘EXTERNAL ACCESS’ is set to ON at the device. If access control is enabled remote access may have to be granted at the device. See Controller Setup for details.

  • If you can ping the controller but HeidenhainPLC outputs an error when connecting please verify that there’s an exception for TCP port 19000 in your firewall. Use our tool Device Port Scanner to check that your controller is reachable via that port.

  • If you get error ‘Access denied’ make sure that you use the correct PLC (OEM) Password or code number.

  • If you get errors you can click on button [Copy], paste the output into a text file or e mail and send it to our developers for further analysis when contacting support.

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Modified: 2023-11-28