NC V Level 3 Stored Programme Systems Past Paper 2024 PDF

# **MARKING GUIDELINE** ## **NATIONAL CERTIFICATE (VOCATIONAL)** ## **STORED PROGRAMME SYSTEMS** ## **NQF LEVEL 3** ### **26 February 2024** This marking guideline consists of 6 pages. ## **QUESTION 1** 1. The executive software determines: * Which functions are available to be used in...

# **MARKING GUIDELINE** ## **NATIONAL CERTIFICATE (VOCATIONAL)** ## **STORED PROGRAMME SYSTEMS** ## **NQF LEVEL 3** ### **26 February 2024** This marking guideline consists of 6 pages. ## **QUESTION 1** 1. The executive software determines: * Which functions are available to be used in the user's application program * How the program is solved * How the I/O is serviced * How the powering up and down of the PLC is managed * When fault conditions exist (Any 4 x 1) (4) 2. **MAINS SUPPLY** | | | | | | | :---------- | :------------- | :-------- | :------------------------ | :------------------- | | POWER SUPPLY  | COMS MODULE  | CPU       | DIGITAL INPUT/OUTPUT INTERFACE | ANALOGUE INPUT/OUTPUT INTERFACE | | ✓          | ✓           | ✓         | | | | | | | | | (Marker to use discretion) (7) 3. * Number and types of input and output points required * Size and type of memory required * Speed and power required of CPU and instruction set * Manufacturer's support and backup (4) [15] ## **QUESTION 2** 1. * The value of the control signal can either be 'ON' or 'OFF'. * An analogue signal that varies smoothly (2 x 2) (4) 2. * Limit switch * Magnetic sensor * Proximity sensor (inductive, capacitance, optical, ultrasonic) (Any 1 x 1) (1) 3. * Pressure sensor * Speed sensor * Level sensor * Weight sensor * Light sensitivity sensor (Any 1 x 1) (1) 4. A sensor gives the status of the machine/application as an input to the PLC and therefore the contacts are considered to be an input to the PLC given the status of a subsystem. (Marker to use discretion) (2) 5. **PLUNGER** | | | | :--------------- | :-------------------- | | HOUSING | CONTACTS | | | | | SPRING | | | | CO | | | NO | | | NC | | | | | | | (Marker to use discretion) (7) 6. A mechanical sensor must make contact with the target, whereas a proximity sensor must detect the presence of the target. (Marker to use discretion) (2 + 2) (4) 7. S (1) [20] ## **QUESTION 3** | ITEM | DESCRIPTION | MARKING | FUNCTION | ADDRESS | | :---- | :------------------------------------------------------------------------------- | :------- | :------------------------------------------------------------------------------------------------------------------------------------ | :------- | | 1 | Mushroom head 22 mm (NC) | E/STOP | Stop working circuit | N/A✓ | | 2 | Detent switch 22 mm (NO) | SW1 | Turn system ON/OFF | N/A | | 3 | Push button 22 mm (NC) | PB1 | Start application | 12✓ | | 4 | Push button 22 mm (NC) | PB2 | Stop application | 13✓ | | 5 | Inductive sensor | S1 | Detect workpiece | 14✓ | | 6 | Indication lamp red 22 mm | H1 | Flashing hazard | Q1✓ | | 7 | Indication lamp green 22 mm | H2 | Standby | Q2✓ | | 8 | Indication lamp amber 22 mm | H3 | Run | Q3✓ | | 9 | 24 VDC relay with 4-contact set | SR | Contact (11-12) Hazard control Contact (22-24) Motor | 11✓ | | 10 | Electromagnetic ejector | M2 | Ejector hub | Q4✓ | | 11 | Contactor 24 VDC coil | K | Motor control | N/A✓ | | | | | | | (Marker to use discretion) (12) When the hardwired emergency stop is activated, the supply to the PLC is not removed from the PLC control unit and the supply to the output actuators are removed (MCR and solenoid valve). A red flashing emergency stop is activated. (Marker to use discretion) (4) * PLC wiring/connection diagram * Working/Controlled/Power circuit * Hard copy of the PLC program/code * Terminal allocation list or lists (4) [20] ## **QUESTION 4** 1.  (Marker to use discretion) (15) 2. Cascaded timers are all turned on at the same time having the timer set to energise at different times, whereas sequenced timers are wired up to energise each other after the pre-time has elapsed. (Marker to use discretion) (2 + 2) (4) 3. * Up counter * Down counter * Up/down counter (3) 4. * Delay on timer * Delay off timer * Retentive/Accumulating timer (Any 2 x 1) (2) 5. * Grafcet/SFC * Function block/FB * PLC LAD (3) 6. * OR * AND * NOT (3) [30] ## **QUESTION 5** 1. * Hardwired faults are input/output wiring, component or termination faults. * Programming faults refer to the logic of the programmed source code. (2 x 2) (4) 2. * Check the on/off switch for operation. * Check if the wiring is correct. * Check if the terminations are secure. (Marker to use discretion) (3) 3. Continuity tester/Ohmmeter (1) 4. * Burnt-out relay coil * Open circuit wiring * Loose termination * High resistance joint at the terminal (Marker to use discretion) (4) 5. * Power supply check * CPU check * Communication test (3) [15] **TOTAL:** 100