PROFINET - IRT Cycle Time of 250us/500us

[IMI-Modrice]

Hello,

We are developing a PROFINET device with "Class C" certification using "AM243 MCU" from Texas Instruments. However, we have difficulties to manage the IRT cycle time of 250us. We can manage 500us cycle time only. In “PROFINET IO Conformance Classes” document, there is a mention about default minimum update rate of 250us. However, there are mentions and examples where you can set only 500us, 1ms etc. in GSDML Specification for PROFINET. Further, we could find a Beckhoff EL6632 controller that have the “Class C” and min IRT cycle time of 500 us.
So, we would like to ask if it’s possible to get the “Class C” certification using data exchange cycle time of 500us or if it’s necessity to get the cycle time of 250us?

Cheers,

[Raik.Zachmann]

Hello,

We are developing a PROFINET device with "Class C" certification using "AM243 MCU" from Texas Instruments. However, we have difficulties to manage the IRT cycle time of 250us. We can manage 500us cycle time only. In “PROFINET IO Conformance Classes” document, there is a mention about default minimum update rate of 250us. However, there are mentions and examples where you can set only 500us, 1ms etc. in GSDML Specification for PROFINET. Further, we could find a Beckhoff EL6632 controller that have the “Class C” and min IRT cycle time of 500 us.
So, we would like to ask if it’s possible to get the “Class C” certification using data exchange cycle time of 500us or if it’s necessity to get the cycle time of 250us?

Cheers,

Hello,
according to the PROFINET specification V2.45, which the actual test bundle refers to, a Class C device shall support the mandatory cycle time of 1ms. So faster cycle times are optional.

Cheers