Edwards STP-iS2207 Series Instruction Manual page 86

DO NOT insert or remove a communication cable while a communication device and a STP
pump are turned ON the power.
5
Communication interface circuit may break down if surge voltage caused by such as potential
difference of communication interfaces or static electricity is applied to communication line.
Communication failure occurs frequently by broken communication interface circuit.
RS485 is available with communication interface circuit according to the environment, but it gets
failure easily. Check the waveform of the differential signal is normal with measuring instruments,
such as an oscilloscope.
D+
D-
MT-89E-001-C
Page 76
STP-iS2207 Series Turbomolecular Pump
a) Normal
Figure 41 - Example of differential signal waveform
D+
D-
b) Abnormal
(abnormal voltage amplitude)