Introduction to Modbus Communication on the Profinet Gateway

After successfully adding the PN1-D25 series Profinet gateway in the TIA Portal, the next step is to configure the Modbus communication parameters. In the Device View interface, you will find two slots for configuring the serial port function modules. Each slot can accommodate up to 32 sub-slots, which are used to configure Modbus command sub-modules. Specifically, Slot 1 corresponds to the serial port status word and control word (for both PNMB Master/PNMB Slave configurations).

• Status Word: PLC devices can retrieve the operational status of the PN1-D25 device through this word.

• Control Word: The PLC device can control the PN1-D25 Profinet gateway via this word.

To adjust the Modbus communication parameters for Serial Port 1 or 2 of the PN1-D25 gateway, select the desired slot (Slot 1 or Slot 2), then click on the Properties option. During this configuration, you must first select the serial port operating mode (PNMB Master/PNMB Slave)—either Modbus RTU master or slave mode. It is worth noting that the PN1-D25 single-port Profinet gateway supports both Modbus RTU Master and Slave modes

Tutorial for Configuring Modbus Communication Parameters on the Profinet Gateway

The following outlines the steps to configure the Modbus communication parameters for the PN1-D25 series Profinet gateway:

PNMB Master Mode:

1. Custom Baudrate:
   When the serial port is configured in Slave mode and requires a custom baud rate, the default setting is 0, indicating that custom baud rate is not enabled. To enable a custom baud rate, set a value between 1200 and 3900000. In this case, the “Baudrate” option will be disabled.

2. Baudrate:
   Standard baud rates include: 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200, 230400, 460800 bps, with the default being 9600.

3. Databits:
   Data bits: 7 or 8 bits, with the default set to 8.

4. Parity:
   Parity settings:

• None Parity (No parity),

• Odd Parity,

• Even Parity,
  with the default being None Parity.

5. Stopbit:
   Stop bits: 1 or 2 bits, with the default set to 1.

6. Max Retry Number:
   This setting determines the number of retries in case of communication failure when the serial port is in Master mode.
   Range: 0-255.

• 0 means no retries,

• 255 means infinite retries,

• 1-254 specifies the number of retries.
  Default: 3.

7. Slave Response Timeout (ms):
   The amount of time the Master will wait for a response from the Modbus slave after sending a Modbus message.
   Range: 0-65535 ms.
   Default: 100 ms.

8. Poll Interval (ms):
   This setting controls the delay between sending Modbus messages after receiving a valid reply from a Modbus slave.
   If the slave device responds slowly, increasing the delay may help avoid communication errors.
   Range: 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 200, 500, 1000 ms, or "No Delay".
   Default: 50 ms.

9. Frame Interval (ms):
   This setting controls the interval between frames.
   Range: 0-65535 ms.

• 0 means automatic frame detection,

• Default: 0.

PNMB Slave Mode:

1. Custom Baudrate:
   Similar to Master mode, if custom baud rate is required for Slave mode, set a value between 1200 and 3900000. If set to a custom value, the “Baudrate” option will be disabled.

2. Baudrate:
   Standard baud rates: 1200, 2400, 4800, 9600, 19200, 38400, 57600, 115200, 230400, 460800 bps, with the default being 9600.

3. Databits:
   Data bits: 7 or 8 bits, with the default set to 8.

4. Parity:
   Parity settings:

• None Parity (No parity),

• Odd Parity,

• Even Parity,
  with the default being None Parity.

5. Stopbit:
   Stop bits: 1 or 2 bits, with the default set to 1.

6. Delay Response Time:
   When the serial port is configured as a slave, this setting defines the delay after receiving a polling command from the master before sending a response.
   Range: 0-65535 ms.
   Default: 0 ms (immediate response).

7. Slave Address:
   This is the Modbus slave address for the serial port when in Slave mode.
   Range: 1-247.
   Default: 1.

Note: Configuration for Serial Port 2 is the same as for Serial Port 1

This guide outlined the steps for configuring the Modbus communication parameters on the PN1-D25 Profinet Gateway using TIA Portal. By following these steps, you can ensure proper communication between the Profinet network and Modbus RTU devices, whether operating as a Master or Slave.