Thermo Fisher Scientific Alpha pH 2000 - Manual (Page 54)

11.4.5 Controller signal of Pulse Frequency Controllers
t ON t OFF
Pulse Length T
Relay
ON
OFF
Time [s]
The output relay of the pulse frequency controller is clock-timed. The pulse
duration t
ON
remains constant at 250mS. Depending on the divergence from
the limit value, the frequency (1/T) is increased or decreased in accordance
with the proportional range Xp.
The following applies:
t
ON
= Const. (250 msec.)
greater divergence
Î greater f (greater frequency)
Xp exceeded Î max. frequency