latch (L) e internal realy (M)

alguien me puede explicar de favor la diferencia entre latch e internal relay de los plc mitsubishi, soy nuevo en esto y tengo esta gran duda.
G: Libro:racias y Bendicione....Misael Glz

Du borde skriva på engelska om du vill ha svar.

Not everyone speak spanish so please write the question in english if you want more help.

I do not speak Spanish, but my I know some Italian, which helped me to understand. He wanted to know difference between latch and internal relays with mitsubishi.
Latch can signify retentive relay or relay which alternates state after every HI signal. With mitsubishi it should mean that it is relay which is configured to be in PLC non volatile memory, so when you power of PLC, and power on it is in same state as before power off.
Internal relays are memory relays M0, M1, M2...., and they can be configured to be latched.

Best regards,
Vuckovic Goran.

I disagree. A "Latch" bit does not typically refer to a memory retentive bit, but to an output bit that remains energized until an "Unlatch" bit with the same address is energized.

Some PLCs call these "Set" and "Reset" bits, and some offer a function block with Set and Reset inputs.

It's been too long since I worked with a Mitsubishi PLC. I don't remember how they handle Latches.

Bit_Bucket_07,

Well, I'm sure that the coils which are ON after SET, and OFF after RESET, are classical coils. There are commands that change coil state from HI to LOW, when you bring HI on input (GX IEC Developer command ALT_M and ALTP_M), as I wrote in previous mail. And with Mitsubishi, word latched is used also for variables that are retentive. Further more, you have option "Latch data backup"...

Best regards,
Vuckovic Goran.

@goghie

As I said, it has been many years since I've worked with a Mitsubishi PLC.

"Latch" typically refers to a latch & unlatch or set & reset bit function, but terminology varies from one manufacturer to the next.

At any rate, who knows if the top poster can even translate our attempts to answer in English.