SCOPE: memory area of the V.E. variable

Depending on the purpose, V.E. variables are assigned either to the channel-specific (var[?].scope = CHANNEL) or the global memory area (var[?].scope = GLOBAL). The two memory areas are of the same size and are set in the case of TwinCAT, for example, via the SystemManager: CNC configuration, CNC task GEO, HLI tab, VE box (enter the number) or in the start-up list via the ext_var_max parameter.

The channel-specific memory area is assigned exclusively to an NC channel, while the global memory area can be read or written by any NC channel of the controller.

This separation does not exist from the PLC's perspective and, as far as it is concerned, all memory areas are equivalent. It has read and write access to each of the memories via several address pointers. 1+channel quantity exists from the PLC's perspective, i.e. a minimum of two memory areas.