Modem control characters

If you need to include non-printable control characters in the hmod_data parameter, you can use any of the following methods:

Include one or more of the escape sequences listed in Table 1, preceded and followed by / (forward slash) characters. For example, to include the CR (carriage-return) character, include /CR/.
Include the decimal value of the control character, preceded and followed by / (forward slash) characters. For example, to include the control character with value 135, include /135/.
Specify the parameter as a hexadecimal array instead of a character string, so that each character in the string is specified by a pair of hexadecimal digits instead of a printable character or escape sequence.