Modbus/TCP (Diagnostics)

The Modbus/TCP Diagnostics page contains the following information. You can refer to Modbus/TCP Settings for information about changing Modbus/TCP parameters. If you want detailed information about the IO-Link Master to Modbus/TCP interface, see the IO-Link Master Modbus/TCP Reference Manual.

Click the PAUSE LIVE UPDATES button to pause the diagnostic data collection. Click the RESUME button restart the data collection.

Click the RESET STATISTICS button to reset the values and gather the latest statistics.

Parameters

Modbus/TCP Diagnostics Descriptions

Active Connections

Displays the current number of active Modbus/TCP connections.

Messages Received from Masters

Displays the number of Modbus messages received from Modbus/TCP Masters.

Responses Sent to Masters

Displays the number of Modbus responses sent to Modbus/TCP Masters.

Broadcasts Received

Displays the number of broadcast Modbus/TCP messages received.

Invalid Message Length Errors

Displays the number of Modbus messages received with incorrect length fields.

Invalid Message Data Errors

Displays the number of invalid message data errors. These errors occur when the IO-Link Master receives a message that cannot be performed due to invalid data.

Invalid Message Address Errors

Displays the number of invalid message address errors. These errors occur when the IO-Link Master receives a message that cannot be performed due to an invalid address.

Unknown Device ID Errors

Displays the number of unknown device ID errors. These errors occur when the IO-Link Master receives a message that is addressed to a device ID other than the configured Slave Mode Device ID.

Invalid Protocol Type Errors

Displays the number of invalid message protocol type errors. These errors occur when the IO-Link Master receives a Modbus/TCP message that specifies a non-Modbus protocol..

Unsupported Function Code Errors

Displays the number of invalid Modbus function code errors. These errors occur when the IO-Link Master receives a message that cannot be performed due to an unsupported Modbus function code.

Configuration Errors

Displays the number of improper configuration errors. These errors occur when the IO-Link Master receives a message that cannot be performed due to an invalid configuration.

No Available Connection Errors

Displays the number of Modbus/TCP connection attempts that were rejected due to no available connections. This occurs when the number of Modbus/TCP connections has reached the limit.

System Resource Errors

Displays the number of system resource errors. These errors indicate a system error on the IO-Link such as operating system errors or full message queues.  These errors typically occur when the PLC(s) are sending messages to the IO-Link Master faster than the IO-Link Master can process them.

First Error String

Text description of the first error that occurred.

Last Error String

Text description of the last error that occurred.

Modbus/TCP Port Specific Diagnostics

Active PDO Controller(s)

Lists the controller interface(s) type, (Class 1 or Class 3), and IP address that are controlling the PDO data.  

PDO Writes to Offline or Read-Only Ports

Displays the number of PDO write messages that were dropped due to any of the following:

  • The port is configured in IO-Link mode:

  • There is no device connected to the port.

  • The IO-Link device is off-line.

  • The IO-Link device does not support PDO data.

  • The PDO Transmit Mode (To PLC) is disabled.

  • The port is configured in Digital Input mode.

ISDU Request Msgs From PLC(s)

Displays the number of ISDU request messages received from the PLC(s) or other controllers. These request messages may contain one or multiple ISDU commands.

ISDU Invalid Requests

Displays the number ISDU requests received over Modbus/TCP with one or more invalid commands.

ISDU Requests When Port Offline

Displays the number ISDU requests received over Modbus/TCP when the IO-Link port was offline. This can occur when:

  • The IO-Link port is initializing, such as after start-up.

  • There is no IO-Link device attached to the port.

  • The IO-Link device is not responding.

  • Communication to the IO-Link device has been lost.

Valid ISDU Responses From Port

Displays the number of valid ISDU response messages returned from the IO-Link port interface and available to the PLC(s). The response messages contain results to the ISDU command(s) received in the request message.

ISDU Response Timeouts

Displays the number ISDU requests that did not receive a response within the configured ISDU Response Timeout.

Unexpected ISDU Responses

Displays the number unexpected ISDU responses. Unexpected responses may occur when an ISDU response is received after the ISDU request has timed out. This typically requires setting the ISDU Response Timeout to a longer value.

Maximum ISDU Request Msg Response Time

Displays the maximum time period required to process all commands within an ISDU request message. The response is not available until all ISDU command(s) contained in the request have been processed.

Average ISDU Request Msg Response Time

Displays the average time period required to process the ISDU request message(s). The response is not available until all ISDU command(s) contained in the request have been processed.

Minimum ISDU Request Msg Response Time

Displays the minimum time period required to process all commands within an ISDU request message. The response is not available until all ISDU command(s) contained in the request have been processed.

ISDU Read Commands

Displays the number ISDU read commands received over Modbus/TCP.

ISDU Write Commands

Displays the number ISDU write commands received over Modbus/TCP.

ISDU NOP Commands

Displays the number ISDU NOP (no operation) commands received over Modbus/TCP.