DCS Voltage Display needs error on unable to communicate with supply
The DCS Voltage display in the control room doesn't understand the difference between a zero value and a failure to read back a device.
This happened today when the network cable on the diblock 2 power supply was knocked loose. It appeared in the control room that the power to diblock 2 was off, but the event displayed showed that a subset of the DCMs where still taking data (one of them was still on, two had been turned off for maintenance)
This is bad in that if we aren't able to talk to one of our supplies we should know this, not simply display zeros.