Commissioning for functional safety standards compliance


In a Functional Safety Standards-compliant installation, you must test the complete device and system setup before deployment of the installation.

Commissioning process

Stage Description

Validate the device wiring to the description in the Product Installation and Wiring section. See Product installation and wiring.


Validate the device settings to the description in the Product Setup. See Safety standards compliance requirements.

Using Modbus/98 protocol to perform commissioning

The device's communication protocol is compliant with the requirements of IEC60730-1:Annex H (SW Class B). Using this communication protocol in place of the standard Modbus interface provides functional safe channel between the device and the system.

You can confirm the device setup and commissioning procedure (Insulation Monitoring and Insulation Fault Detection Testing) by ensuring the values set on the device are as expected (Modbus/98 Write function) and the values read from the device are reliable (according to Class B IEC 60730-1 annex H).

The protocol is an add-on to the standard Modbus protocol (as defined in the Modbus Serial Line Protocol and Implementation Guide v1.02 from Modbus.org) using a custom function code: 98 (0x62). Refer to the dedicated Modbus/98 protocol document for a detailed description of the protocol and implementation guide of the master driver.

The protocol relies on a session mechanism to enclose the communication in a safe structure, as follows:

Multiple Modbus/98 Read/Write operations can happen during an active session, but it is mandatory to close the session at the end of a given sequence.

NOTE: The master in the system must confirm that the sessions are closed. A timeout set during the open session sequence allows you to automatically close a session after a given time.

Using this protocol provides the following features:

  • Data integrity: The integrity of the data transmitted and processed by the device across the device and system failures, by using dedicated error management mechanisms embedded in the protocol.

  • Communication sync: The transmissions are sequential and in a valid time window.

  • Secure link: The master and slave devices identify both ends of the active communication session using unique tokens re-initialized at every session.

You can use both protocols (standard and /98) at the same time in the device. But to comply with all the functional safety standards requirements the system which integrates the device must do the following configuration sequence (using Modbus/98 protocol):

Parameter Address Register Value Comment
dec hex dec hex
Lock standard Modbus 754 2F2 755 2F3 1 (ON) Read function is still active
Lock HMI with password 3014 BC6 3015 BC7 0000...9999 Set password
3015 BC7 3016 BC8 1 Activate password protection
NOTE: The listed parameters are stored in non-volatile memory and are therefore persistent over a power cycle.

The device cannot confirm if the received data is correct and applicable to the system. It can only confirm the integrity of the received data.

QR Code is a registered trademark of DENSO WAVE INCORPORATED in Japan and other countries.

Was this helpful?