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 Allen Bradley PLC PWM (Pulse Width Modulation) error codes   Following Table Shows PWM instruction Error Codes with Description. Error Code Error Name Description -2 OverlapError An output overlap is detected.   Multiple functions are assigned to the same physical output.   This is a configuration error.   The controller faults and the User Fault Routine does not execute. -1 Output Error An invalid output has been specified.   Output 2 and output 3 are the only valid choices.   this is a configuration error.   The controller faults and the User Fault Routine does not execute. 0 Normal 0=No error 1 HardstopError This error is detected whenever a hardstop is detected.   This error does not fault the controller.   It is automatically cleared when the hardstop condition is removed. 2 OutputForced Error The configured PWM output (2 or 3) is currently forced.   The forced condition must be remov...

Networking Basic for PLC Engineer   In the world of computers, networking id the theory of connecting 2 or more computing devices together for the purpose of sharing important data. Networks are built with mix of hardware & software. Basically Networks are categories into      Peer to Peer Networks      Client Server Networks IEEE has developed different communication standards which are summarized in following table. IEEE 802 Standards   Network Cabling   Cabling is medium through which information usually moves from one network device to another. There are several types of cables used in networks. Some Guidelines for Installing Cables   When running cable , it is best to follow few basic rules:   Always use more cable than you need. Leave plenty of slack Test every part of a network as you install it. Even if it is a brand new, it may have problems that will be difficult to isolate later.   Stay at least 3 fee...

Assignments on PLC Ladder Programming A) Simple PLC ON-OFF Instructions: Develop OR, AND, NOT, NOR, NAND, and EX-OR logic using two toggle switches and output is given to a pilot lamp. A fan is started and stopped from three different locations. Each location has a start and stop pushbutton. Develop a ladder program for a motor with START and STOP pushbuttons. Green lamp should be ON, when motor is running and motor should stop suddenly when bearing temperature is high, with red lamp indication. In a certain bank, each of three bank officers has a unique key to the vault. The bank rules require that two out of the three officers be present when the vault is opened. Develop the ladder program that will unlatch the door and turn on the light when two of the three keys are inserted. Draw the ladder program for following application. There are four hazardous inputs to the alarm system that goes ON when a fault occurs. The sequence is, If any one fault occurs, nothing will happen. If any tw...