Configure Modbus Access

Super users, administrators and device users can configure the settings for Modbus serial and TCP from the CLI or the web interface. The Modbus configuration options are the same in both interfaces. For more information see respective section:

• Configure Modbus Serial and TCP from the CLI

• Configure Modbus Serial from the Web Interface

• Configure Modbus TCP from the Web Interface

The recommended settings are 19200 baud rate, 8 bit data, even parity, 1 stop bit.

1. Log in to the CLI.

2. To see the configuration options type modbus ?.

   Setting	Command	Argument	Description
   Help	?		Shows the command help for Modbus.
   Modbus serial status	–a	enable | disable	Enables or disables Modbus serial.
   Baud rate	–br	2400 | 9600 | 19200 | 38400	The data transfer rate in bits per second.
   Parity	–pr	even | odd | none	The parity bit or check bit.
   Mode	-m	8e1 | 8o1 | 8n2 | 8n1	Default modes for the serial configuration: 8o1 – 8 bit data, odd parity, 1 stop bit 8e1 – 8 bit data, even parity, 1 stop bit 8n1 – 8 bit data, no parity, 1 stop bit 8n2 – 8 bit data, no parity, 2 stop bits
   Slave address	–s	1 - F7	The slave address or unique ID of the target device in hexadecimal.
   Reset settings	–rDef		Resets all the Modbus settings to default.
   Modbus TCP status	–tE	enable | disable	Enables or disables Modbus TCP.
   Modbus TCP port number	–tP	502, 5000 – 32768	Sets the Modbus TCP port number to the entered value.
   Modbus TCP timeout	-tTO	1 – 64800 seconds, 0 = never	Set for how long the Modbus TCP communication can be active before timing out.

1. Log in to the web interface.

2. Navigate to Configuration > Network > Modbus > Serial.

3. Configure the Modbus serial settings:

   • Access: Enabled if box is checked.

   • Baud Rate: Select a baud rate [2400 | 9600 | 19200 | 38400].

   • Mode: Select a parity.

   • Target Unique ID: A unique number for the NMC, needs to be different for each NMC on a network [1 – 247].

4. Click Apply to save any changes.

   NOTE: Reboot the NMC to apply changes. From the web interface select Control > Network > Reset/Reboot for options.

1. Log in to the web interface.

2. Navigate to Configuration > Network > Modbus > TCP.

3. Configure the Modbus TCP settings:

   • Access: Enabled if box is checked.

   • Port: Enter port used [502, 5000 – 32768].

   • Communication Timeout: Enter a timeout time in seconds or select never (can also enter 0 seconds for never).

   • Keep-Alive: When enabled, an acknowledge request will be sent to any open connection that has been idle for a long time (2h). This option is independent of the communication timeout setting.

4. Click Apply to save any changes.

   NOTE: Reboot the NMC to apply changes. From the web interface select Control > Network > Reset/Reboot for options.