Serial Data Integrity
It is the verification that the command frame sent on a wireless remote control has reached the receiver uncorrupted. IEC 62745 lists serial data integrity and error detection as an explicit requirement; a corrupted frame is not accepted as a command and is silently discarded.
The radio environment is noisy: interference, reflection and a weak signal can change bits. A single bit flipping is dangerous enough to turn an up command into a down command. For this reason the frame carries not only the command but also verification information.
A typical frame consists of these parts:
- The preamble sequence that synchronises the receiver.
- The set's identity or address code.
- The command bytes, that is, which channel is active in which direction.
- The integrity field, that is, a checksum or a cyclic redundancy code.
The receiver recalculates this field; if the result does not match, the frame is dropped and the watchdog counter is not reset. In other words, corrupted packets arriving continuously leave the system motionless. The practical result is this: under heavy interference the remote control does not cause a wrong movement, it becomes unresponsive. Behind a complaint of intermittent response there is most often this protection mechanism and a real source of interference.
The context in which this term is used: Wireless Crane Remote Control Selection Guide