WOODWARD XU2-AC relay power supply


Terminals A1/A3 are to be used for voltages from 50 – 750 V DC or from 36 – 520 V AC

Category: SKU: XU2-AC Tag:
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From the above response time estimation formula, it can be seen that the response time of the input signal is determined by the scanning cycle. The scanning cycle depends on the hardware configuration of the system on the one hand, and on the other hand, it is determined by the instructions and the number of instructions used in the control software. During the debugging process of the automatic control system of the block forming machine, the automatic pushing process (the process of sending the block from the forming table to the conveyor) starts, It depends on the completion signal of the forming process to start. The process of transporting bricks is completed while the process of feeding plates is completed, and the control system is notified that the next forming process can be completed.

From the perspective of program execution sequence alone, the arrangement of control timing is correct. However, during debugging, it was found that the actual control timing of the system is that after the first molding process is completed, the automatic pushing process is not carried out, but the next molding process is directly started. In this case, the first reaction of designers and users is generally to suspect program design errors. After repeatedly checking the program, no errors were found, and it was only then that it was considered possible that the response time of the instruction had caused an issue. The control system of the block forming machine is a huge system, with 500 to 600 software control instructions. The start signal of the forming process is generated by the end signal of a forming process and the signal with a board. In this case, the HR002 signal is scanned during a certain scanning cycle, and the position pushing process is executed to directly proceed to the next forming process. This may be caused by the long response time of the input signal. In this case, due to the hardware configuration cannot be changed, the number of instructions cannot be changed, and during the processing, We managed to make adjustments in the software to ensure that the signal for the end of the molding process occurred earlier, and the problem was resolved.

Software reset
The most common type used in PLC programming is an internal relay called a holding relay. The holding relay of PLC is from HR000 to HR915, totaling 10 × There are 16, and the other type is a total of 48 timers or counters from TIM00 to TIM47 (CNT00 or CNT47) (different models of PLC holding relays have different number of timer points). Among them, the maintenance relay realizes the function of memory, which memorizes the operating status of the mechanical system and controls the normal timing of the system’s operation. In order to achieve safety, timeliness, and accuracy in the timing control, the control signal (generated by the maintenance relay) is usually used to terminate the previous mechanical action when a mechanical action is completed, The situation where the time relay for initiating the next mechanical action cannot be reset normally,

Before starting the machine, if the hold relay is not forcibly reset, mechanical equipment malfunction will occur. When designing the system, the usual method is to set a hardware reset button, which can force the hold relay, timer, counter, and high-speed counter to reset when needed. In the debugging of the control system, it was found that if the hold relay, timer, counter, and high-speed counter are used too many times, The function of hardware reset often does not work, which means that the method of hardware reset sometimes cannot be accurate and timely reset the internal relays, timers, and counters of the PLC, resulting in the control system not functioning properly. During the debugging process, manually setting the software reset signal as an internal signal can ensure that the relay is effectively reset and the system operates normally under any circumstances.