Building a Programmable Logic Controller with a PIC16F648A Microcontroller

 

3 Contact and Relay-Based Macros

 

In this chapter, the following contact and relay-based macros are described:

1. ld (load)

2. ld_not (load not)

3. not

4. or

5. or_not

6. nor

7. and

8. and_not

9. nand

10. xor

11. xor_not

12. xnor

13. out

14. out_not

15. in_out

16. inv_out

17. _set

18. _reset

The ile deinitions inc, included within the CD-ROM attached to this book, contains all macros deined for the PIC16F648A-based PLC The contact and relay-based macros are defined to operate on Boolean (1-bit) variables. The working register W is utilized to transfer the information to or from the contact and relay-based macros, except for macros in_out and inv_out Let us now briefly consider these macros.

TABLE 3.1Truth Table and Symbols of the Macro ld

3.1 Macro Id (load)

The truth table and symbols of the ...