The timer OFF-delay instruction is a retentive timer instruction 11. Internal bit C5:0/CU is on when the input to the count up instruction C5:0 is open ID: E 12. There are two types of PLC counter instructions. 13. The content of an accumulated register in the countdown instruction decrements whenever there is a low-to-high counter input switch transition 14. The accumulated register for counter instruction C5:0 is addressed as C5:0.ACC. 15. The counter done it for the counter instruction C5:1 is addressed as C5:1/DN. 16. The count up instruction C5:0 in a fixed SLC 500 PLC uses two sixteen bit registers. 17. The content of an accumulated register in the count up instruction increments whenever there is a low to high counter input switch transition 18. Internal bit CS:0 CD is on when the input to the count up instruction C5:0 is closed. 19. In a subtract instruction, sources A and B can be the content of integer registers N7:0 and 7:1. respectively 20. In a multiply instruction, the result carnot be placed in the integer register N7:2 21. The destination in the add instruction must nor be a register 22. There are several advanced math instructions that are available in the Allen-Bradley SLC 503, 5LC 5704 and SEC 5/05 processors 23. Forced conditions must be used with extreme caution, 24. Occupational Safety and Health Agency (OSHA) regulations require that technicians must not use forced conditions when the plant is in normal operation, 25. The Allen-Bradley fixed SLC 500 PLC has ten inputs. 26. SLC 500 PLCs have five indicator lights: Power, PLC run, CPU fault, forced 1/0 and battery low 27. Rockwell RSLogix 500 software can be used for troubleshooting to find PLC falts and take corrective actions to solve problems 28. The PLC run light indicates when power has been applied to the PLC and the processor is energie 29. In addition to checking the indicator lights, technicians must also maintain a clean environment around the PLC cabinets.