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Serial Module skips/sends/returns wrong data
Brother.Ed from United States [3 posts] |
9 year
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Greetings STeven! Thank you for this impressive software.
I am trying to identify and sort various Legos on a moving belt and blow them off with air into the correct bin. I am using an Arduino Uno that looks for a RelayNumber (integer) on the serial port, then calculates the number of counts from a proximity switch before firing the correct relay. It seems to work well when I send numbers from the keyboard, but now I want to send them from RoboRealm.
RoboRealm is able to identify the parts going past the camera but I can't seem to get the "ID" number to reliably make it to the serial port. While watching the serial Console, some ID numbers never get sent even though display_variables shows a proper ID. Sometimes the Arduino reports back a number that was not sent.
I have been studying thread 4995 and have modeled my system similarly. Please see attached. I have checked "Wait for Reply".
Do you think I have a computer error? (Old XP Machine)
Do I have a strategy error? (I hope to control 20 relays eventually)
Is it possible that the Console is not fast enough to catch the return string from Arduino?
Thanks in advance. I am very new to vision systems!
Brother.Ed
 Brother_Ed.zip
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Steven Gentner from United States [1446 posts] |
9 year
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Ed,
We found in the past that communicating with an Arduino can cause issues. That's why the Arduino modules include a CRC (checksum) to ensure that the data was sent correctly. Its possible for characters to go missing so you have to watch for that.
What I would do in your case is convert the number to a single byte. You can do this in the serial module by using
\[RelayNo]
which would send a single byte instead of a bunch of ascii characters which could be received out of order. With a single byte, there isn't anything to get lot and is also a lot faster.
You will have to ensure that no relay is above 255 but I think that's ok in your situation.
You will also have to change your Arduino code to now receive a single binary character and use that directly ... which again is actually easier than dealing with an ascii string.
Try that change and see how it fairs.
STeven.
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Brother.Ed from United States [3 posts] |
9 year
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Thanks for the info. I will try it as soon as I can!
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Brother.Ed from United States [3 posts] |
9 year
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Sending only a byte seemed to help a lot! I also added a short delay in the Arduino code to give the serial time to finish processing before moving on and that seemed to help also.
. . .
readByte=Serial.read();
delay(20);
. . .
Thanks!
Brother.Ed
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