How does the internal relay operate?
- ID:
- 62
- Issued:
- Jun 17th, 2010
- Updated:
- May 17th, 2013
When turning ON the internal relay by a transfer instruction, the relay stays ON even after the condition before the transfer instruction becomes false. Why?
- ANSWER
- The internal relays are operated by the OUT, SET/RST, or high-level instructions. They instruct different operations.
(1) The OUT instruction writes “1” in the memory if the previous condition is true, and writes “0” if false.This means that this instruction writes either "0" or "1" every time it is executed.
(2) The SET instruction writes “1” in the memory if the previous condition is true, and writes nothing if false.The RST instruction writes “0” in the memory if the previous condition is true, and writes nothing if false.This means that the memory is not changed (the status is held) if the previous condition is false.
(3) High-level instructions write ON/OFF in the memory in a 16-bit batch if the previous condition is true, and writes nothing if false.
This means that the instructions hold the latest status if the previous condition is false.
When programming, please keep in mind that the internal relay operation varies depending on the instruction. - RELATED CATEGORIES
