SENA Serial_IPTM Redirector 4.3 - Manual (Page 65)

For example:
AT+SCPW?
NONE
OK
AT+SCP=c:\sample.pem
OK
AT+SCPW?
INVALID
OK
AT+SCPW=raining-cats-and-dogs
OK
AT+SCPW?
VALID
OK