Why does PI200 RAMP IN amplitude decrease when the SLOW sign jumper is fitted?

RAMP IN and the selected slow-path output are mixed through equal 10 kΩ resistors before the SLOW OUT buffer.

For a low-impedance RAMP IN source and a high-impedance load:

• SLOW jumper at +1 or -1: SLOW OUT ≈ (RAMP IN ± slow-path output) / 2
• SLOW jumper removed: SLOW OUT ≈ RAMP IN

Fitting the jumper therefore reduces the RAMP IN contribution by approximately a factor of two even when the slow-path output is 0 V.

Disabling SLOW INT does not disconnect the slow path. It remains proportional at low frequencies, so a nonzero ERROR signal can add to or subtract from RAMP IN depending on the jumper position.

SLOW OUT has a 1 kΩ output impedance. A lower load impedance causes additional attenuation.

RAMP IN is mainly intended for open-loop scanning of the slow actuator. See the PI200 user guide.