Process variables

R0 to R7: Registers in the internal RAM of the terminal

The process variables can be used in addition to the actual process image. Their function is specific to the terminal.

R0 to R5: Terminal-specific registers

The function of these registers depend on the respective terminal type (see terminal-specific register description).

• R6: Diagnostic register
  The diagnostic register can contain additional diagnostic information. Parity errors, for instance, that occur in serial interface terminals during data transmission are indicated here.

• R7: Command register
  High-Byte_Write = function parameter
  Low-Byte_Write = function number
  High-Byte_Read = function result
  Low-Byte_Read = function number