This variable is currently read-only and it indicates what type of code is
being sent across the DS1 interface by the device. The values mean:
SENDNOCODE - sending looped or normal data
SENDLINECODE - sending a request for a line loopback
SENDPAYLOADCODE - sending a request for a payload loopback
SENDRESETCODE - sending a loopback termination request
SENDQRS - sending a Quasi-Random Signal (QRS) test pattern
SEND511PATTERN - sending a 511 bit fixed test pattern
SEND3IN24PATTERN - sending a fixed test pattern of 3 bits set in 24
SENDOTHERTESTPATTERN - sending a test pattern other than those
described by this object