Topic : Why L1 (Serial Coil) is blown when CIF31 cable is connected ?

Q) One of customer had send in total 4 units of faulty CS1W-CIF31, complained all cannot communicate with the computer.
All units are in working in condition after a new commication IC was replaced except one of them is due to inductor (connect to pin 5 of connector) open circuit.
Our customer would like to know why the failure of communication IC is so frequent. Is there any correction action to prevent problem from reoccurring.
This CIF31 is used with CS1W-CN226 connect to the peripheral port of CS1 CPU.

A) This is caused by large Inrush current when CS1W-CIF31 is conencted.
Possible cause:
1) 24VDC is Hot grounded
2) Non Isolated DC power supply is used



Repair Log of CIF31 cable :
MAX3243EEAI+T may be stronger than MAX3243EEAI. (Ref: )