TIOL111: Port class B

I do not know of any TI reference designs that specifically implements the class B type port. However, there is no difference in the IO-Link device transceiver for the class A or class B and no special selection is needed. The same transceiver can be used in either port types. The differences in the ports are more system level in how the extra unused pins of the connectors are used.

For the connection technology in IP65/67, one possible connector is the 5-pin M12 plug connector.

For both Port Class A and B, pin 1 is used for L+, pin 3 is used for L-, and pin 4 is used for C/Q. The IO-Link transceiver (such as the TIOL111) is typically only connected to pins 1, 3, and 4.

For Port Class A (Type A), the functions of pins 2 and 5 are not specified and the manufacturer defines these functions. Pin 2 is usually assigned with an additional digital channel.

For Port Class B (Type B), an additional supply voltage is provided and is suitable for the connection of devices that an increased power demand. Pins 2 and 5 are used to provide additional (galvanically isolated) supply voltage.

Therefore, if the system uses a class B port, the transceiver will be connected to the same pins of the connector as it would be for a class A port, and pins 2 and 5 would be used for a second isolated supply voltage for other devices such as sensors, or actuators, etc. on the board.

Regards,
Jonathan

I think your understanding is generally correct, however, I think this is somewhat system specific and could vary from system to system. 

According to the IO-Link specification, IO-Link masters should supply 200 mA per port for the port class A, that is the power supply to the sensors and electronics (L+).  For sensors and low current modules, this 200 mA is plenty of current.  There is typically an LDO or DC/DC on the module to create the lower digital voltages i.e 3.3 V or 5 V from the 24 V L+ voltage to power the MCU and sensor devices.  The TIOL111-5 and TIOL111-3 have internal LDOs that create a 5 V and 3.3V voltages respectively.

For the port class B, there is a second power supply used for higher current device such as actuator to use an example.  The IO-Link specification does not specify a maximum current for this supply and it is only limited by the connector rating.  However, in the master data sheets, they often specify a maximum total current for this actuator supply voltage that must not be exceeded in total across all ports.

It is my general understanding that this actuator supply in the port class B is galvanically isolated, but I would defer to the master datasheet for confirmation as I can see it possible that they could not be fully isolated from the L+ source supply inside the master.  If you chose a master that is galvanically isolated, and you want to maintain the isolation between the MCU and the actuator or other device powered from the isolated supply, then yes I would say the control IO's should also be isolated.  But this is really up to the system requirements and design using a master and components that support isolation if it is required.

I don't have personal knowledge that isolation is mandatory for class B, or that is is optional with some being isolated and others not isolated.  I have seen documentation stating that this is typically galvanically isolated, I assume that some are and some are not isolated which is why I am suggesting you check the master datasheet for verification.

Regards,
Jonathan