Delay between dmw_send and light turning on using WT32-ETH01?

[MatDec]

Hi,

I am using this library to communicate with LED dimmers that accept DMX input (s1-dr dimmers).
The dimmer consists of 2 channels, where the LED light bulb is on channel1.
Using a WT32-ETH01 board (ESP32 board with builtin ethernet) and a MAX485 TTL to RS485 Converter Module, I can send commands to the dimmer.

However, there seems to be a delay (~0.5s - 1s) between the serial.println showing it has turned on the light, and the dimmer turning on the light. The sketch simply switches the light on and off in a loop (ON - wait 1s - OFF - wait 1s).

I am using a modified version of the Arduino_DMXWrite.ino sketch.
I can see the loop runs much faster, as the 'Serial.println("dmx_send_num OK")' and ' Serial.println("dmx_wait_sent OK")' are written to the serial output multiple times per second.

I cannot find any 'soft start' or some kind of delay parameter on the dimmer.
I also terminated the bus with a 120ohm resistor.
Any ideas on why this might be?

bool on = false;

void loop() {
  /* Get the current time since boot in milliseconds so that we can find out how
    long it has been since we last updated data and printed to the Serial
    Monitor. */
  unsigned long now = millis();

  if (now - lastUpdate >= 1000) {
    /* Turn the LED light bulb ON and OFF every 1 second on DMX channel 1. */
    
    if (on == false){
        data[1] = 0xFF;
        dmx_write(dmxPort, data, DMX_PACKET_SIZE);
        Serial.println("LED ON");
        on = true;
    } else {
        data[1] = 0x00;
        dmx_write(dmxPort, data, DMX_PACKET_SIZE);
        Serial.println("LED OFF");
        on = false;
    }
  }

  /* Now we can transmit the DMX packet! */
  dmx_send_num(dmxPort, DMX_PACKET_SIZE);

  Serial.println("dmx_send_num OK")  
  /* We can do some other work here if we want. */

  /* If we have no more work to do, we will wait until we are done sending our
    DMX packet. */
  dmx_wait_sent(dmxPort, DMX_TIMEOUT_TICK);
  Serial.println("dmx_wait_sent OK")  

}