Chapter 8, Problem 7P

Program Plan Intro

Count-Up (CTU) Counter:

• The CTU counter refers to an up counter
• This counter is used to count an event that occurs logically or externally and places that value in the counter’s accumulator.
• The accumulated value can even be maintained during false rung conditions and can be reset back to 0 using reset instruction.

Count-Down (CTD) Counter:

• The CTD counter refers to a down counter
• It decrements the accumulated value at each false-to-true transition and it also retains the accumulated value as soon as an on/off power cycle occurs.

Explanation of Solution

b.

Accumulated count of counter CTD:

• It is given that 20 on/off transitions occur at input “A” and 5 on/off transitions occur at input “B”.
• The CTU and CTD counters are addressed at the same location “C5:2”.
• The up-counter and down-counter operates simultaneously to increment and decrement the accumulated count value...

Explanation of Solution

c.

State of output A:

• Here, the accumulated count value of CTU counter is 15.
• The output “A” gets activated only when it receives CU signals from the counter “C5:2”.
• But, the preset value is set for 10...

Explanation of Solution

d.

State of output B:

• Here, the accumulated count value of CTD counter is 15.
• The output “B” gets activated only when it receives CD signals from the counter “C5:2”.
• But, the preset value is set for 10...

Explanation of Solution

e.

State of output C:

• Here, the accumulated count value of up/down counters is 15 and it is greater than the preset value 10 in the counters addressed at “C5:2’...