VDC HV control
Relay Box with 8 relays (channels) controlled by RPi board is used to limit trip current and prevent trips for VDC high voltage line during HV on/off.
Two of them have been installed in Left and Right HRS at the end of March, 2017.
Relay box consists of 8 relays and 8 resistors with 68Mohm nominal. Resistor is connected in series between output of hv channel and VDC hv line, or shortened by relay.
RPi board is used as TCP/IP server to control relays by commands from clients. RPi board that used in HV crate (rpi8(left),rpi7(right)) runs shim-server to control modules in crate.
Shim-server will be used as client and will send commands to relay box server to switch relay ON (closed, shortened resistor) or OFF (open, resistor in).
The next logic will be used in shim-server to control relays:
- for all commands to hv channel that controls VDC
Command format for relay box server is the same as used by LeCroy HV system (examples):
- set relay channel #1 to ON (closed)
LD S0.1 RLY 1
- set relay channels #0,#2 to ON (closed) and channels #1,#3-#7 to OFF (open)
LD S0 RLY 1 0 1 0 0 0 0 0
- get status of all relays channel (1 - is ON, 0 - is OFF
RC S0 RLY