Technical Reference > CtAPI Functions > Reading Data Using the CTAPI Functions > Bit shifting when reading digital arrays

Bit shifting when reading digital arrays

When digital types are read, CitectSCADA may adjust the starting position of the first point. This is done to improve the performance of the digital read. For example, if you start reading an array of digital values, CitectSCADA may read several digitals before the start of the array, and the data will be offset. When CitectSCADA shifts the bits, extra data will be read from the I/O Device. CitectSCADA may shift the data up to 15 bits, resulting in an extra 2 bytes of buffer space necessary for reads. Therefore, always use digital buffers which contain 2 bytes extra.