Thanks for that. This still doesn't help the error I am receiving though - I still cannot send a basic string into the code - the code does work if I am doing it in Max. Do you have an example of how comport ought to be set up to output a string of 5 numbers?

Ok, I'll try this.
Still, if I just send a test message with a string like
[1 1 255 255 1 ] -> [comport]
it should light two of them, but when I send that I still get the error, which made me think something else is going wrong.

(the 5 vs 6 values is just my brain melting, thanks for the float tip, it's something I noticed but hadn't internalised yet)

Which works using the following max patch:

The arduino code is:

#include <FastLED.h>
#define LED_PIN     7
#define LED_PIN2    6
#define LED_PIN3    5
#define LED_PIN4    4
#define LED_PIN5    3
#define NUM_LEDS    1
CRGB leds[NUM_LEDS];
CRGB leds2[NUM_LEDS];
CRGB leds3[NUM_LEDS];
CRGB leds4[NUM_LEDS];
CRGB leds5[NUM_LEDS];
int incoming[5] = {0, 0, 0, 0, 0};



void setup() {
  FastLED.addLeds<WS2812, LED_PIN, GRB>(leds, NUM_LEDS);
  FastLED.addLeds<WS2812, LED_PIN2, GRB>(leds2, NUM_LEDS);
  FastLED.addLeds<WS2812, LED_PIN3, GRB>(leds, NUM_LEDS);
  FastLED.addLeds<WS2812, LED_PIN4, GRB>(leds2, NUM_LEDS);
  FastLED.addLeds<WS2812, LED_PIN5, GRB>(leds, NUM_LEDS);

  Serial.begin(9600);


}
void loop() {
  if (Serial.available() > 0) {
    // read the incoming byte:
  }
  incoming [0] = Serial.read();
  incoming [1] = Serial.read();
  incoming [2] = Serial.read();
  incoming [3] = Serial.read();
  incoming [4] = Serial.read();
  leds[0] = CRGB(incoming [0], incoming [0], incoming [0]);
  FastLED.show(); 
  leds2[0] = CRGB(incoming [1], incoming [1], incoming [1]);
  FastLED.show(); 
  leds3[0] = CRGB(incoming [2], incoming [2], incoming [2]);
  FastLED.show(); 
  leds4[0] = CRGB(incoming [3], incoming [3], incoming [3]);
  FastLED.show(); 
  leds5[0] = CRGB(incoming [4], incoming [4], incoming [4]);
  FastLED.show(); 
}```

Which works using the following max patch: 
![Screenshot 2021-12-16 at 21.18.20.png](/uploads/files/1639685913315-screenshot-2021-12-16-at-21.18.20.png)

Hey, sorry, was posting on my mac, here's the patch from the pi:

The weird thing is that if I run comport in the help files, I can send data directly as:
[int]->{% 255]->[comport 1 9600], but if I do the same thing in my patch it doesn't work

Hey,

I've been struggling with puredata on a raspberry Pi4 all day. After finally managing to install comport, I'm running into an issue outputting to my arduino.
I'm trying to send a 6 figure string to the comport (opened on port 1, serial rate 9600), but I'm getting the error:
"Write failed for 0 bytes, error is 2"
I'm not really sure why this is happening - I ran an identical patch in Max that worked without issue but this doesn't seem to work. I'm assuming that there is an issue with the way the data is formatted but I don't exactly know what the issue is.

Thanks!