Color spec

Color Spec is a string that specifies what mix of colors to use in the light source. The string is a sequence of letter(s) (r - red, g - green, b - blue, w - white or f - farred) followed by what percentage you want that color to be. For example, "r90b10" calls for 90% red, and 10% blue. There are many shortcuts:"r90" means 90% red, and any other colors available will evenly make up the remaining 10%.

  • Recognized colors are r, g, b, w, and f (f is farred, in the fluorometer)
  • 6800-01/A (fluorometer) has r, b, and f, but f is never enabled unless explicitly asked for.
  • 6800-02 (small light source) has r and b.
  • 6800-03 (large 4 color light source) has r, g, b, and w.
  • If the sum of requested percentages is <100, the difference is divided equally between any remaining unspecified colors. If there are no unspecified remaining colors, the specified colors are scaled to sum to 100.
  • If the sum of requested percentages is >100, they are scaled to sum to 100.
  • There is no order dependency. That is, "r30w50" is the same as "w50r30".
Table 3‑4. Examples of Color Spec settings and their effect on the three light sources.
Color Spec 6800-01/A 6800-02 6800-03
% red % blue % farred % red % blue % red % green % blue % white
r90 90 10 0 90 10 90 3.3 3.3 3.3
r90b10 90 10 0 90 10 90 0 10 0
r90b9f1 90 9 1 90.9 9.1 90 0.5 9 0.5
w100 50 50 0 50 50 0 0 0 100
w25 50 50 0 50 50 25 25 25 25
r50g30b20 71.4 28.6 0 71.4 28.6 50 30 20 0

"w25" for the 6800-01, -02: There is no white to set to 25%, so red and blue are each 50%.

"r50g30b20" for the 6800-01, -02: red is 50, blue is 20, but there is no green. That leaves 30% unaccounted for, so the 50 and 20 are scaled up to 71.4 and 28.6.

Optional Limits: Upper case color letters (R,G,B,W,F) can be added to a color spec to limit that particular color(s) to some level of intensity in (mol m-2 s-1). For example, the recommended color spec for the fluorometer is "r90B40" which will keep set blue LEDs to 10% of the total, or 40 mol m-2 s-1, whichever is lower. The reason for this is to have just enough blue for stomatal control and keep the actinic and the fluorescence measuring beam as spectrally close as possible.

Important side effect: Note that the 6800-02 and 6800-03 (but NOT the 6800-01) will dim the LEDs any time a color change is specified while the light is on. Thus any specification with a limit specifier (upper case color letter) has the potential of causing a color change (and momentary light intensity dip) any time a new setpoint target is specified. So, for example, ramping a lamp with Auto Control with the spec "r90" will cause smooth changes in light, but with "r90B40", the lamp will momentarily dim at each new setpoint above 400, since the blue has to be reduced by varying amounts to keep it at 40. Again, this is not an issue with the fluorometer, but it is with the other light sources.