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I'm having a little trouble getting this function of my code to write out:

void SendCTRL (String &input) 
{
  const char *hin = input.c_str();    // Get character array
  int clen = input.length()/2;
  char cmd[clen+1]; // Leave a byte for null terminator
  for (int i=0; i < clen; i++)
  {
    cmd[i/2] = dehex(hin[i])<<4 | dehex(hin[i+1]);
  }
  cmd[clen] = 0;                     // Null-byte terminator
  digitalWrite(SSerialTxControl, RS485Transmit);  // Enable RS485 Transmit   
  RS485Serial.write(cmd);   // Send string someplace
  delay(clen*20);        // Wait for write to complete? What rate?
  digitalWrite(SSerialTxControl, RS485Receive);  // Disable RS485 Transmit
  Serial.print(" CMD Sent:");
  Serial.println(cmd);
}

byte dehex(char c) 
{
  // Get nibble value 0...15 from character c
  // Treat digit if c<'A', else letter
  return c<'A'? c & 0xF : 9 + (c & 0xF);
}

Input is a series of ASCII-encoded hex digits and I'm trying to get the output to print the byte values of the hex.

Right now cmd returns no value when called which makes me think I'm not writing to it correctly. Any advice would be greatly appreciated.

The Code Below now works:

void SendCTRL (String &input) 
{
  const char *hin = input.c_str();    // Get character array
  int clen = input.length()/2;
  unsigned char cmd[clen+1]; // Leave a byte for null terminator
  for (int i=0; i < 2*clen; i+=2)
  {
    cmd[i/2] = dehex(hin[i])<<4 | dehex(hin[i+1]);
  }
  cmd[clen] = 0;                     // Null-byte terminator
  digitalWrite(SSerialTxControl, RS485Transmit);  // Enable RS485 Transmit   
  for (int i=0; i< clen; i++)
  {
  RS485Serial.write(cmd[i]);   // Send string someplace
  //Serial.write(cmd[i]);
  }
  delay(clen/4);
  digitalWrite(SSerialTxControl, RS485Receive);  // Disable RS485 Transmit
  Serial.println();
  
}

byte dehex(char c) 
{
  // Get nibble value 0...15 from character c
  // Treat digit if c<'A', else letter
  return c<'A'? c & 0xF : 9 + (c & 0xF);
}

byte dehex(char c) 
{
  // Get nibble value 0...15 from character c
  // Treat digit if c<'A', else letter
  return c<'A'? c & 0xF : 9 + (c & 0xF);
}

Input is a series of ASCII-encoded hex digits and getting the output to print the byte values of the hex.

I'm having a little trouble getting this function of my code to write out:

void SendCTRL (String &input) 
{
  char *hin = input.c_str();    // Get character array
  int clen = input.length()/2;
  char cmd[clen+1]; // Leave a byte for null terminator
  for (int i=0; i < clen; i++)
  {
    cmd[i/2] = dehex(hin[i])<<4 | dehex(hin[i+1]);
  }
  cmd[clen] = 0;                     // Null-byte terminator
  digitalWrite(SSerialTxControl, RS485Transmit);  // Enable RS485 Transmit   
  RS485Serial.write(cmd);   // Send string someplace
  delay(clen/4);        // Wait for write to complete
  digitalWrite(SSerialTxControl, RS485Receive);  // Disable RS485 Transmit
  Serial.print(cmd);
  Serial.println(" CMD Sent");
}

byte dehex(char c) 
{
  // Get nibble value 0...15 from character c
  // Treat digit if c<'A', else letter
  return c<'A'? c & 0xF : 9 + (c & 0xF);
}

Input is a series of ASCII-encoded hex digits and I'm trying to get the output to print the byte values of the hex.

Right now cmd returns no value when called which makes me think I'm not writing to it correctly. Any advice would be greatly appreciated.

I'm having a little trouble getting this function of my code to write out:

void SendCTRL (String &input) 
{
  const char *hin = input.c_str();    // Get character array
  int clen = input.length()/2;
  char cmd[clen+1]; // Leave a byte for null terminator
  for (int i=0; i < clen; i++)
  {
    cmd[i/2] = dehex(hin[i])<<4 | dehex(hin[i+1]);
  }
  cmd[clen] = 0;                     // Null-byte terminator
  digitalWrite(SSerialTxControl, RS485Transmit);  // Enable RS485 Transmit   
  RS485Serial.write(cmd);   // Send string someplace
  delay(clen*20);        // Wait for write to complete? What rate?
  digitalWrite(SSerialTxControl, RS485Receive);  // Disable RS485 Transmit
  Serial.print(" CMD Sent:");
  Serial.println(cmd);
}

byte dehex(char c) 
{
  // Get nibble value 0...15 from character c
  // Treat digit if c<'A', else letter
  return c<'A'? c & 0xF : 9 + (c & 0xF);
}

Input is a series of ASCII-encoded hex digits and I'm trying to get the output to print the byte values of the hex.

Right now cmd returns no value when called which makes me think I'm not writing to it correctly. Any advice would be greatly appreciated.