PEAK-System Forum

I wanted to know how much overhead and jitter is added by the module i.e.

1. the time taken by the module to put the signals onto the CAN bus from the moment the signals are applied to its USB interface
2. the time taken by the module to deliver the signals from the CAN bus to its USB interface.

It would be great if you could provide the information. If there’s a document that provides the information, it would be great.

Hello,

There are many factors involved in this, such as:

- Which operating system is used
- Is this operating system real-time capable?
- When referring to Jitter: On Transmission? On Reception? Cyclic messages or not?
- etc.

USB related latency:

This is depending on the payload of the USB Data.
The USB Subsystem sends out the package when the Transport buffer is full, or when the timeout is reached.
This could result in only one CAN Frame being part of the USB Transfer. You need to calculate a 1ms latency on top of it.

The Timestamp itself is the real ACK Time of the received CAN Frame - this is be done in the Firmware on the USB Device.
So you have the absolute time when the CAN Frame was received in your CAN Msg Structure, receive it in your API with a 1ms delay.
Same for sending. Calculate a 1ms delay and you are on the save side.

Please give us some more infomation so we can clearify further.

Best Regards

Marvin