Chapter 4
Implementation details
Additional information about the use and implementation of the S7Drv driver in the REX Control System is gathered in this chapter.
- In PLC world the dot is used as the delimiter when referencing binary signals (e.g. M2.3). This is not possible in the REX control system and therefore the underscore character is used.
- Special references to memory areas are implemented for LOGO devices. The <area> string has these additional options to correlate with the LOGO notation: Q<index> for relay outputs, AI<index> for analog inputs, AM<index> for analog memory flags, AQ<index> for analog outputs.
- LOGO uses the I, Q and M areas only for Boolean signals. Analog signals are in special
areas (area code):
16 NI 17 NQ (read-only) 18 AI 19 AQ 20 AM 21 NAI 22 NAQ (read-only)
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