Chapter 12. Data Handling
Timers, counters, and individual internal relays are all concerned with the handling of individual bits, that is single on/off signals. Shift registers involve a number of bits with a group of internal relays being linked (see Chapter 11
). The block of data in the register is manipulated. This chapter is about PLC operations involving blocks of data representing a value; such blocks are called words
. A block of data is needed if we are to represent numbers rather than just a single on/off input. Data handling consists of operations involving moving or transferring numeric information stored in one memory word location to another word in a different location, comparing data values, and carrying out simple arithmetic operations. ...