1. Control System Applications (2)
Programming Logic Controllers
PLCs
Lect. 9
Dr. Tarek Ahmed Mahmoud

2. Outlines Numerical Processing Word Objects Word Format Word Types
Numerical Instructions

3. Word Objects Word Format
Word objects are addressed in the form of words of 16 bits
Word Format 1
16384
+/-
8192 14 15
Bit position
Bit state
Bit value 13 2 3 4 5 6 7 8 9 10 11 12
4096
2048
1024
512
256
128 64 32 16
Bit 15 at 0 is a positive value.
Bit 15 at 1 the word is a negative value (negative values are expressed in two's complement logic).

4. Word Format (cont.) Decimal 1579 (max : 32767, min :-32768)
Hexadecimal 16#A (max : 16#FFFF, min : 16#0000)
Alternate syntax : #A536.

5. Word Types in NANO PLC 1- Immediate values 2- Internal words
- They are used to store values during
the operation.
- They are stored in the data memory.
- They are read or written to directly by the program.
- They are used as working words.
%MW to %MW255

6. Word Types in NANO PLC (cont.)
3- Constant words
They store constant values
Their contents can only be written or modified in the CONFIGURATION editor.
- They are read-only access by the program.
%KW to %KW64
4- Function Block Words
- They are read or modified in the program.
- Such as %TMi.P and %Ci.P, %Ti.v, etc.

7. Word Types in NANO PLC (cont.)
5- System words
Words have special functions related to the PLC operation
%SW to %SW127
%SW30 Shows execution time of the last PLC scan cycle
6- I/O exchange words
Words %IW and %QW are used to exchange data between PLCs.

8. Word Types in NANO PLC (cont.)
Bit objects extracted from words
% Word object : Xk
k = 0 to 15
% MW5:x6
Bit position 6 of internal word %MW5.

9. Word Types in NANO PLC (cont.)

10. Numerical Instructions
Numerical instructions generally apply to 16-bit words
They are written
- Between square brackets (instruction list)
[ Instruction ]
- In a rectangular (in ladder diagram).
Instruction

11. Numerical Instructions
1- Assignment instructions
These are used to load operand Op2 into operand Op1
Syntax :
[Op1:=Op2]
Op1 is a memory word
Op2 is a memory word or
an immediate value
Example
LD 1
[%MW10:%MW20]
%MW10:= %MW20

12. LDR %I0.3
[%MW10:=100]

13. Numerical Instructions
2- Arithmetic instructions
: Add two operands
: Subtract two operands
* : Multiply two operands
/ : Divide two operands
SQRT : Square root of an operand
INC : increment an operand

14. - Examples

15. Numerical Instructions
3- Comparison Instructions
> : test if greater than.
>= : test if greater than or equal.
< : test if less than.
<= : test if less than or equal.
= : test if equal.
<> : test if not equal (different from).
The result is 1 when the comparison requested is true.

16. - Examples

17. Numerical Instructions
4- Logic instructions
AND : AND (bit-wise) between two operands
OR : Logic OR (bit-wise) between two operands
XOR : Exclusive OR (bit-wise) between two operands
NOT : Logic complement (bit-wise) of an operand

18. - Examples LD %M0 [%MW0 := %MW10 AND 16#FF00] LD %I0.3
[%MW102:= NOT (%MW100)]
LD 1
[%MW0 := %KW5 OR %MW10]

19. Numerical Instructions
4- Shift instructions
SHL (op2,i) logic shift of i positions to the left.
SHR (op2,i) logic shift of i positions to the right.

20. Application Automatic Traffic Lights steps green yellow red time
15 sec. 1
4 sec. 2
12 sec. 3
3 sec.