PLC M8000-M8990 is a special internal relay of Mitsubishi PLC.
M8000 is a special auxiliary relay. m8000 is always closed during operation. m8001 and m8002 are initialization pulses. When plc is just started, it closes a cycle, but 8001 is normally closed, 8002 is normally open, m8011, 8012, 8013. It is a time pulse with periods of 10ms, 100ms, 1000ms (one second), m8020, m8021, m8022, which are standard real bits, representing benefits, zeros, and endings.
There are other special auxiliary relays, which are commonly used. If you want to know more, you need a programming manual.
M8000-Operation monitors normally open contacts, and the PLC is always ON when it is running.
M8001-Operation monitors normally closed contacts, and the PLC keeps OFF when it is running.
M8002 – Initialize pulse normally open contact, ON one scan cycle when PLC is running.
M8003 – Initialize pulse normally closed contact, OFF one scan cycle when PLC is running.
M8011, M8012, M8013, and M8014 generate clock pulses of 10ms, 100ms, 1s, and 1min, respectively.
Special auxiliary relay.
(2) Coil type. The PLC performs a specific action after the coil is driven by the user program.
M8033 – If its coil is energized, the output image memory and data register contents are maintained when the PLC is stopped.
M8034 – If the coil is energized, the output of the PLC is completely disabled.
M8039 – If its coil is energized, the PLC will operate according to the scan time specified in D8039.