Applies To:
  • CitectSCADA 5.00 to 5.41
  • CitectHMI 5.00 to 5.41
Summary:
When I compile a project using the SIMPPI driver (Siemens S7-200 Serial), I get the error:

Bad IO Device Variable

It points to the address of a tag, but it appears to be a legal address.

 

Solution:
The help page correctly lists the minimum and maximum value for each PLC address, but releases prior to Citect 5.42 fail to mention that some addresses must be a multiple of 2 or 4.

The following data types must be a multiple of 4 (e.g. 0, 4, 8, etc.):

ID
QD
MD
VD
VF

These data types must be a multiple of 2 (e.g. 0, 2, 4, etc):

IW
QW
MW
VW

The multiple of 2 or 4 requirement is determined by the SIMPPI.DBF file. The affected data types have a template string ending with %/2 or %/4.

 
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