Programmable logic controllers $($PLCs$)$ are frequently used for the control of mechatronic systems.

$($a$)$ The listing of the structured text $($ST$)$ program is given below. What is the value of variables

$$Q$7$a$1$ and $$Q$7$a$2$ after the first execution of $$Program$1?$

$($marks $2)$

$($b$)$ What is the value of the variable RESULT after the first execution of Program$2?$

$($marks $2)$

$(9$ of $18)$

$($c$)$ The listing of ST program is given below.

$($i$)$ An error message occurs when building $$Program$3.$ Briefly detail why this error

message occurs.

$($marks $3)$

$($ii$)$ Write a corrected version of $$Program$3$ in your answer booklet.

$($marks $2\mathrm{.}5)$

$($iii$)$ Based upon your corrected version of $$Program$3,$ what is the value of the variable

$$out$$ after the $2$

nd execution of $$Program$3?$

$($marks $3)$

$($d$)$ What is the value of the variable DISPLAY, after the execution of the ST code$-$snippet below,

when Ctrl$=14?$