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Is there a deterministic behavior when sending multiple commands in succession
In Help and Getting Started
Is there a deterministic behavior when sending multiple commands in succession
In Help and Getting Started
Is there a deterministic behavior when sending multiple commands in succession
In Help and Getting Started
Max
Dec 21, 2021
So there are actually two parts in this question. 1) Can you control different motion aspects using different commands one after another? The answer here is no, any motion command will cancel any effects of the previously issued motion commands (but there are commands that allow you to control more than one parameter at the same time, e.g. position & speed) 2) What is the maximum command rate? All commands in RMD protocol that I saw are using the standard CAN frame and always use 8 data bytes. Assuming worst-case scenario for the CAN bus stuffing bits, the bus throughput will be around 6800 frames per second at 1MHz bus rate. The motor will always respond with the frame of the same structure to any accepted command keeping the bus busy, which effectively halves the frame rate and results in around 3400 frames (or commands) per second. I've tried sending the next command immediately after receiving response from the previous one, and one motor seems to readily accept a little bit over 3000 commands per second (hence ~0.3ms between commands). 6 motors on the same bus seem to accept a bit over 500 commands (in case where all 6 motors receive their commands in sequence). I would not build any solution based purely on the delay (be 1ms or 5ms or whatever) as there could be bus errors, interference, something else keeping the bus busy etc. It seems safe to issue another command immediately after the motor responded to the previous command. Similar calculations will be valid for RS485 if you take in account stuffing bits (absent in RS485) and lower bus rate supported by the RMD controller (compared to the CAN bus version), it will be approx 1/8 of the numbers above. The controller spec (found that in the RMD-* Series Motor Selection Table documents found in the Downloads section of this website) says the communication rate for CAN is 2KHz for 1MHz bus which is pretty close to my calculations above and results in 0.5ms (and not 5ms) between commands.
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RMD-L max torque/current in the speed-loop control
In Help and Getting Started
Torque value
In Help and Getting Started
Max
Dec 07, 2021
Nope
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Max

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