MVAJ21T1GB0771B ALSTOM 开关量输入/输出卡件

MVAJ21T1GB0771B ALSTOM 开关量输入/输出卡件

1．通用辅助继电器 FX系列PLC的通用辅助继电器没有断电保功能。在FX系列PLC中，除了输入继电器和输出继电器的元件号采用八进制外，其他编程元件的元件号均采用十进制。
断电保护示意图
断电保护示意图
如果在PLC运行时电源突然中断，输出继电器和通用辅助继电器将全部变为OFF。若电源再次接通，除了因外部输入信号而变为ON的以外，其余的仍将保持为OFF状态。
2. 电池后备/锁存辅助继电器 某些控制系统要求记忆电源中断瞬时的状态，重新通电后再现其状态，电池后备/锁存辅助继电器可以用于这种场合。在电源中断时用锂电池保持RAM中的映像寄存器的内容，或将它们保存在EEPROM中。它们只是在PLC重新通电后的第 一个扫描周期保持断电瞬时的状态。为了利用它们的断电记忆功能，可以采用有记忆功能的电路。设图3–7中X0和X1分别是起动按钮和停止按钮，M500通过Y0控制外部的电动机，如果电源中断时M500为1状态，因为电路的记忆作用，重新通电后M500将保持为l状态，使Y0继续为ON，电动机重新开始运行。

MVAJ21T1GB0771B ALSTOM 开关量输入/输出卡件
1. General purpose auxiliary relays FX series PLC general purpose auxiliary relays do not have power failure protection. In the FX series PLC, except for the input and output relays, the component numbers of other programming components are in decimal.
Power failure protection diagram
Power failure protection diagram
If the power supply is suddenly interrupted while the PLC is running, the output relay and the general auxiliary relay will all be turned OFF. If the power supply is switched ON again, the rest will remain OFF except for those turned on by external input signals.
2. Battery backup/latching auxiliary relays Some control systems require memory of the instantaneous state of power interruption, and reproduce its state after re-powering, and battery backup/latching auxiliary relays can be used in such cases. Use a lithium battery to preserve the contents of the image registers in RAM or save them in EEPROM during power outages. They only remain in the transient state of power failure for the first scan cycle after the PLC is re-energized. In order to take advantage of their power off memory function, a circuit with memory function can be used. Let X0 and X1 in Figure 3-7 be the start button and the stop button respectively. M500 controls the external motor through Y0. If M500 is in 1 state when the power supply is interrupted, because of the memory function of the circuit, M500 will remain in l state after re-energization, so that Y0 continues to be ON and the motor starts to run again.

MVAJ21T1GB0771B ALSTOM 开关量输入/输出卡件