Chapter 7, Problem 6P

Program Plan Intro

Retentive Timer ON (RTO):

• RTO refers to an on-delay timer.
• RTO counts the time-based intervals as soon as the instruction becomes true.
• It retains the accumulated value as soon as instruction goes false or when power cycle occurs.

Explanation of Solution

b.

Required time:

• In “rung 2”and “rung 3”, the two RTO timers are interconnected.
• Here, the “present” value of “rung 2” is “2900” and the “present” value of “rung 3” is “1780”.
• Add these two present values to get the time required to produce the output.
• The sum of the two values is “4680”...

Explanation of Solution

c.

Conditions to be satisfied:

• The power required to be supplied to “L1” and close the input “PB1” contacts to turn the “rung 4” to “true”.
• Once, “PB1” becomes true, the “rung 2” star...

Explanation of Solution

d.

Status of the output:

• The RTO instruction used in the given diagram stores the timed count of timer and counts the time even if the power is lost or restored.
• The “rung 3” is required to activate the “DN” sign...

Explanation of Solution

e.

Result when PB2 is ON:

• If the input PB2 is “ON”, then the reset instructions of the timers “T4:1” and “T4:2” will make the “rung 1” as “true”...

Explanation of Solution

f.

Required accumulated time:

• The “rung 2” becomes “true” and the RTO instructions are started to execute when PB1 input contact is closed.
• The timer “T4:1” starts timing as long as the accumulated value attains the present value “2900”...