Applies To:
  • CitectSCADA 1.20 2.01

The SIEMENS Protocol supports a signed BCD format peculiar to Siemens PLC's. Some users may require a standard BCD format. 

To use an unsigned BCD format use the CITECT.INI option SiemensBCD in the SIEMENS. For example:


The option applies to both the BCD and LONGBCD data types.

Technical Detail:

The default format supported by the SIEMENS Protocol is a Siemens version of BCD that uses the first four bits as a sign indicator. For example, 999(dec) is written as F999(bcd) and +999(dec) is written as 0999(bcd). The unsigned format uses all four BCD digits as digits therefore allowing numbers 0 to 9999.