Page 413 - Programmable Logic Controllers, Fifth Edition - Mobile version

PART 6 REVIEW QUESTIONS

1. Compare the graphical representation of a function 8. Which pins of a function block are inputs and
block diagram to that of a logic ladder diagram. which are outputs?
2. Name the four basic elements of an FBD. 9. Explain the role of input and output wire
3. What do the solid and dashed interconnecting lines connectors.
between FBD function blocks indicate? 10. How does the program scan function for an FBD
4. What is an Add-On instruction? program?
5. How are the input and output parameter options for 11. Explain data latching as it applies to function block
a function block set? inputs.
6. What does the dot on an input or output pin of a 12. How is a function block feedback loop created?
function block indicate? 13. What is the Assume Data Available indicator
7. Compare the functions of input and output refer- used for?
ence tags. 14. Outline how an FBD program is initiated.

PART 6 PROBLEMS

1. Write an FBD program that will cause the output, 4. Modify the Up/Down counter FBD program
solenoid SOL_1, to be energized when pushbutton (Figure 15-111) to include the following pilot
PB_1 is open and PB_2 is closed, and either limit lights:
switch LS_1 is open or limit switch LS_2 is closed. • PL_1 to come on when a part enters
Assume all pushbuttons and limit switches are of the • PL_2 to come on when a part exits
normally open type. • PL_3 to come on when the buffer zone is full
2. Modify the motor start/stop FBD program 5. Modify the test accumulated value of a counter FBD
(Figure 15-109) to include a second start/stop program (Figure 15-112) as follows:
pushbutton station. • PL_1 to be on for an accumulated count between
3. You are required to change the on-delay time of the 0 and 5
10 second timer program (Figure 15-110) to 1 minute. • PL_2 to be on for an accumulated count of 12
What changes would have to be made to the FBD • PL_3 to be on at all times except for when the
program? accumulated count is 15.

394 Part 6 Function Block Programming

pet73842_ch15_333-394.indd 394 03/11/15 7:34 PM