Looking for some help regarding timing and networks
Posted: 27 Jan 2021, 18:07
So a bit of background. We are creating a robotic installation which is running on ROS (Robotic Operating System) and plan on controlling some of the peripheral hardware with raspberry pi (or equivalent) which is how we found the revolution Pi products. ROS can be installed on a raspberry pi and i've seen a few questions on this forum where people are asking about it. It seems so long as we pick one of the ones with larger flash memory then we should be ok on that front.
some of the peripheral hardware communicates over ethernet and we were consider using the connect or connect+ to control this hardware (and from a ROS point of view act as a remote node) however it looks like we would be limited to a single standard ethernet port given that the remaining port would need to go to the general network. This leads me onto my questions
- what is the data rate between expansion modules to the pi (Both for expansion modules communication (such as ethercat) and IO ones, I read that there was 5ms cycles? does this mean 200Hz is the maximum frequency we will be able to get updates from our devices on the expansion modules?)
- how fast is the TCP/IP on built in ethernet? (i.e. we will be getting quite a lot of time sensitive data into one of these connections and need to process it, slightly, before forwarding onto the other port where our ROS server is running, is there a known latency introduced between the two?)
- Can we use a network switch to route multiple TCP/IP connections through to the pi? We have multiple ethernet devices and would ideally like to connect them to a single pi to keep cost of the cell down.
some of the peripheral hardware communicates over ethernet and we were consider using the connect or connect+ to control this hardware (and from a ROS point of view act as a remote node) however it looks like we would be limited to a single standard ethernet port given that the remaining port would need to go to the general network. This leads me onto my questions
- what is the data rate between expansion modules to the pi (Both for expansion modules communication (such as ethercat) and IO ones, I read that there was 5ms cycles? does this mean 200Hz is the maximum frequency we will be able to get updates from our devices on the expansion modules?)
- how fast is the TCP/IP on built in ethernet? (i.e. we will be getting quite a lot of time sensitive data into one of these connections and need to process it, slightly, before forwarding onto the other port where our ROS server is running, is there a known latency introduced between the two?)
- Can we use a network switch to route multiple TCP/IP connections through to the pi? We have multiple ethernet devices and would ideally like to connect them to a single pi to keep cost of the cell down.