Read request

A read request is a request from the MCB task to read a location on an SIB attached to this serial port, and to return the data in buffer allocated to the device in the vxWorks I/O system. The ioctl() call will be used to issue a read request, and a subsequent ioctl will return the status of the operation. Upon a successful read, the data will be returned in the data member of the mcbTransaction structure.