Mechanical Engineering Exam at Cork Institute of Technology - Engineering Systems & Design, Exams of Systems Engineering

Download Mechanical Engineering Exam at Cork Institute of Technology - Engineering Systems & Design and more Exams Systems Engineering in PDF only on Docsity! Cork Institute of Technology Bachelor of Engineering in Mechanical Engineering - Award (NFQ Level 7) Summer 2007 Engineering Systems and Design Engineering Systems (Time: 3 Hours) Answer Four Questions Examiner: Dr. M. J. O’Mahony Mr. J. Connolly Dr. P. Delassus Q1. The structure of programmable logic controllers (PLCs) can be split into four basic components: Input interface. Output interface. Processing unit (CPU). Memory unit. Describe the relationship between and the function of the above four basic components. (25 Marks) Q2. The following sequence is to be implemented using a PLC and monostable directional control valves. A+ B+C+B-C- B+C+B-C- B+C+B-C-A- (ii) How many groups are required are required if a cascade system is used? (5 Marks) (iii) Draw a SiemensS7 ladder diagram for the above sequence. Use a counter to simplify the solution. Assume that all internal PLC relays have to be latched. (20 Marks) Use the attached pneumatic circuit (FigQ2) as a aid to numbering the solenoids and limit switches. The following nomenclature is to be used: A, B, C:Double acting pneumatic cylinders A+, etc:The extend stroke of cylinder A A+p: The pilot signal to cause the A+ stroke of cylinder A A-p: The pilot signal which initiates the return stroke of cylinder A Ad: The logic complement of A-p, used to reset single solenoid valves by disabling the latch function. V,W: Internal PLC relays which can be set on or off Vp: Signal which sets relay V _ Vp: Signal which resets relay V Vd: The logical complement of Vp which disables relay V by disabling the latch. Use the symbol table given in Table Q2. Q3. Describe the operation, function and application of (i) Shift registers (12 Marks) (ii) Interrupts (8 Marks) in programmable logic controllers. (iii) Describe one method to initiate an interrupt using a Siemens S7 222 PLC. (5 Marks) Name Address Comment Final_Count VW0 Variable memory word VW0 contains the ending value in the loop count (FINAL). Initial_Count VW10 Variable memory word VW10 contains starting value in the loop count (INITIAL). Current_Count VW20 Variable memory word VW20 contains the current loop count (INDEX). First_Address VB100 Variable memory byte VB100 is the first address under which a value is saved. Table Q5 Figure 5 To en 1O5LAL UTP vwso: ar es ext — el oun ven a i | sole ea oot svoro0dn__ou Network? Use FORIVEXT to Copy Wass to ¥aulable Maarory Ares oa FOR I er yerz7| 10x vento mt vero" enn, OV exo} —> near ourp act ‘ADO ex enop-—>} fact 00 Networks t-rex) Figure Q5 ait