Function blocks 5 Function blocks 5.1 FB_SPA At the input all available values for the location definition and type of calculation are specified. The calculation is performed during a function block cycle. The results are immediately available at the output. Due to the complex internal calculation steps processing takes system performance. VAR_INPUT VAR_INPUT stTime :ST_SPA_TIMESTRUCT; (* local date and time (year, month, day, hour, minute, seco nd) *) fTimezone :LREAL; (* Observer time zone (negative west of Greenwich) *) (* valid range: -18 TO 18 hours, error code:
8 *) fDelta_t :LREAL:=66; (* Difference between earth rotation time and terrestrial ti me *) (* It is derived from observation only and is reported in this *) (* bulletin: http://maia.usno.navy.mil/ser7/ser7.dat, *) (* where delta_t = 32.184 + (TAI-UTC) + DUT1 *) (* valid range: -8000 to 8000 seconds, error code: 7 *) fLongitude :LREAL; (* Observer longitude (negative west of Greenwich) *) (* valid range: -180 to 180 degrees, error code: 9 *) fLatitude :LREAL; (* Observer latitude (negative south of equator) *) (* valid range: -90 to 90 degrees, error code: 10 *) fElevation :LREAL; (* Observer elevation [meters] *) (* valid range: -6500000 or higher meters, error code:
11 *) fPressure :LREAL:=1000; (* Annual average local pressure [millibars] *) (* valid range: 0 to 5000 millibars, error code: 12 *) fTemperature :LREAL; (* Annual average local temperature [degrees Celsius] *) (* valid range: -273 to 6000 degrees Celsius, error code; 13 *) fSlope :LREAL; (* Surface slope (measured from the horizontal plane) *) (* valid range: -360 to 360 degrees, error code: 14 *) fAzm_rotation :LREAL; (* Surface azimuth rotation (measured from south to projection o f *) (* surface normal on horizontal plane, negative west) *) (* valid range: -360 to 360 degrees, error code:
15 *) fAtmos_refract :LREAL:=0.5667; (* Atmospheric refraction at sunrise and sunset (0.5667 deg is typ.)*) (* valid range: -5 to 5 degrees, error code: 16 *) eFunction :E_SPA_FunctionCode:=eSPA_ZA; (* Switch to choose functions for desired output *) END_VAR TS3900 13 Version: 1.1