When digital types are read, Citect SCADA 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, Citect SCADA may read several digitals before the start of the array, and the data will be offset. When Citect SCADA shifts the bits, extra data will be read from the I/O Device. Citect SCADA 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.
Published June 2018