| Applies To: |
|
| Summary: |
| The Schneider TWIDO PLC uses different
addressing and always starts at 0 for Registers, Inputs, Outputs
etc but the classic Modicon PLC using Modbus always starts at 1.
This could cause problems and confusion when configuring the
addresses in CitectSCADA. |
| Solution: |
| In the Modbus the holding area are (4x)
and in the Twido are %Mw. The Coil area in the Modbus are (0x) and
in the Twido are %m. In other words if a Variable tag in
CitectSCADA addresses 40001 to the Modbus driver then this will
address the first Twido register i.e. %mw One remark: Make sure that you shift the address because the Twido addressing always starts at 0 and Modbus always starts at 1, so the mapping will be as follows. %mw0 -> 400001 There is also a link to a site shown below that refers to the addressing of Twido inputs through Modbus: http://www.control.com/1026228083/index_html The main extract from this site is as follows: In Vijeo Designer select IEC61131 syntax for the Modbus equipment (Twido). You will then have access to %Mx or %MWx:Xx (memory bits, and Memory words (%MW). It is not possible to look at %Q and %I directly you will have to use an operate block in the twido software to move the inputs into a memory word, you can then read 'each' individual bit of the %MW. For example write an operate block containing '%MW100:=%I0.0:12' This will copy the values of input %i0.0 - %I0.11 into %MW100. You can then create discrete variables starting %MW100:xo
etc. |
| Keywords: |
| Schneider, TWIDO, Modbus, Modnet |
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