A bit is a memory address that contains either a '0' ("False") or a '1' ("True").
When changing the value in a bit, the bit is "set" (given a value of 1) or "reset" (given a value of 0).
Thus a "set bit" is a bit that has a value of 1.
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A "word" is an integer (number), typically consisting of 16 consecutive bits. Typically we think of that word as having a value -- say '5' -- but we can also look at that value as a binary value -- '000101'. Thus, in this word that has a value of 5, the first (usually called the 'zero' bit) and the third (the 'two' bit) are set. This can be a useful technique for packing information, with the HMI reading a single register, but getting lots of information about it.
What the meaning of each bit-in-the-word (or "word bit" as you're trying to use it, although I've never heard that phrase before) is up to you and the PLC programmer(s).
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Sometimes it works out that way. Sometimes things are well enough planned out ahead of time so that both teams know what "rules" are going to used to define addresses. Thus the HMI team can link to registers that the PLC team hasn't created yet, but when they do, the links will work.
Time is money, and the bosses can't have someone sitting around waiting for someone else to be done before they can get started. A little bit of planning, a bit of asking "If I can't do X, then what CAN I do?" can speed things up greatly.
Good luck.
Well thanks for the info and in the Weintek software it has Set word and word lamp my mistake on the bit word.