[xcu_r1] Powering motors pertubates also gauge's reading

This issue was initially filed into JIRA by 'arnaud.lefur' at 02/Feb/16 9:02 AM as ICS-24.
This issue was assigned to 'Steve Hope'.

When the motors are powered on, it made pcm to fail to read gauge value from time to time, in a very cyclic way.

text="sending '~320010074002=?106\r\n'"
08:41:04.846958 .xcu_r1 51 xcu_r1 d text="received 'Error: RD_485'"
08:41:04.848455 .xcu_r1 51 xcu_r1 f text="command failed: RuntimeError('Error reading or writing: Error: RD_485',) at /home/pfs/products/Linux64/ics_xcuActor/1.2.1/python/xcuActor/Controllers/PCM.py:63"

When we power off, everythings back to normal.