Each analog input or output signal is specified by a “signal number”. When configuring a controller, some functions require the specification of an analog signal. This is typically accomplished by entering a signal number via a web-based form. If a signal number of zero is specified, this indicates that no signal is to be used. Negative signal numbers are not allowed. The analog signal numbers are also used by the Signal class in GPL procedures.
Externally, an analog value is a voltage level between +10 and -10 VDC. This value is converted to or from a numeric value within the Guidance Controller. To perform the conversion, a scale factor, offset, and clipping limits are applied. These conversion factors are configurable and are defined in the parameter database.