iman,
Could somebody teach me what is differencies between
ASCII text and Modbus,for inter-device communication.
Now quite frankly I haven't heard of Modbus. I can tell you
that ASCII, American Standard Code for Information Interchange,
is simply a numeric code for letters, numbers, a few special
characters and some control characters. ASCII is widely used,
probably the standard, in the US. I would think that it may be
the standard for the world now, to have to convert among
various codes in international message handling would seem
an herculean task. When comparing communication codes
there are a number of considerations. Back when this sort
of communication was far less reliable the EBCDIC code
was sometimes used because it was more easily error
checked. I have never worked in an environment where
EBCDIC was in use.
Other considerations might be, what kind of information
is being transmitted. I don't know what is done to ASCII
when special characters are required, ones that look
strange to us who are accustomed only to English.
I haven't answered your question, but at least you know that
your message was received. This forum seems to have people
of widely varied skills and knowledge, I'm certain that someone
will be able to help you. It might help if you told us the context
in which you know about the Modbus code.
Is there an interface for these?
If the only difference between two code is the numerical values
conversion is quite simple. A look up table is often used, the
position in the table for one code is matched with the position
in the other table. A program has two pointers, one pointed
at the start of each table. The first table is searched
while incrementing both pointers until a match is found.
Then the value pointed to by the second pointer is the
converted character. There may be some programmers
in the group who know a more sophisticated conversion
scheme. I've never needed one.
Jim
