Transcript that the CAN standard arbitration is not used

FP420
Low and high voltage supply
Henning E. Larsen,
INFN/Univ. of torino
[email protected]
April. 2007
Twisted pair cables for communcation
into the tunnel
• Requirements (CAEN solution):
– 500m twisted pair of good quality
– min. 8 pairs + wires for service power
– CAN bus 250kBit/s, Clk 650kHz, Reset pulse
• Tests done:
– Borrowed 279m of cable in stores, Looped 2 times to get 558m.
– Applied test equipment of RS485 protocol and RS485 with opencollector mode compatible with CAN bus arbitration.
• Asynchronous 8 bit data in one burst (serial comm)
• Clock transmission.
Test setup
USB-RS485
279m SCEM 04.21.52.124.4,
6 pairs
USB-RS485
Loop back
+5V
120Ω
Data
Model of test setup
558 cable
E
ADM485
240Ω
120Ω
120Ω
Results: CLK, 558m cable
SCEM 04.21.52.124.4
CLK 1MHz
over 558m of cable
Black: Cable in
Red: Cable out
CLK 1MHz
over 558m of cable
Duty cycle out=45%
Black: Receiver out, ADM485. Duty cycle=55%
Red: Receiver out, MAX8089, Duty cycle=60%
Results: Lab. test, data transmission
using cable SCEM 04.21.52.124.4
• 1Mbit/s, 558m.
• No errors detected
• Driver: ADM485
+5V
Data
• Driver: ADM485 in
”open-collector” mode
558
cable
E
Conclusions on cable test
• Data transmission tests have verified that it works up to
1Mbaud in a lab environment with the cable SCEM
04.21.52.124.4.
• Clock transmission has been tested to work with a duty
cycle distortion of <10% at 1MHz
• This family of cables would support the CAN bus
communication at 125kBaud over 500m
• It would also support CAN-250kBaud under the condition
that the CAN standard arbitration is not used. Not clear if
arbitration has to be available. Depend on the software.
Commercial: Caen
CMS/Atlas counting room
Atlas or CMS
SY1527
Slow control
A1676A
A1676A
Crate Ctl
Crate Ctl
LHC Tunnel
EASY 3000
A3486
EASY 3000
A3501
A3501
A3501
12ch
A3501
12ch
A3501
12ch
A3501
HV
12ch
A3501
HV
12ch
HV
12ch
HV
12ch
HV
HV
HV
A3009
A3009
A3009
12ch
A3009
12ch
A3009
12ch
LV
12chLV
12ch
LV
LV
LV
2x48V
Power
EASY 3000
A3501
A3501
A3501
12ch
A3501
12ch
A3501
12ch
A3501
HV
12ch
A3501
HV
12ch
HV
12ch
HV
12ch
HV
HV
HV
A3009
A3009
A3009
12ch
A3009
12ch
A3009
12chLV
12chLV
12chLV
LV
LV
Cryostat 1
A3486
EASY 3000
Cryostat 2
FP420
FP420
FP420
FP420
FP420
FP420
FP420
FP420
FP420
FP420
pocket
pocket
pocket
pocket
pocket
pocket
pocket
pocket
pocket
pocket
2x48V
Power
Commercial: Caen
Cable:
500m
A3009 LV
A3501 HV
A3009 LV
A3501 HV
A3486 48V Power
•Modules
•Delivery not possible before summer 2008 due to LHC production bottle neck. Only few
samples by mid 2007.
•CAN bus link over 500++m require slow down to 250kbit/s. This is not yet tested but should be
ok. According to CAEN this Requires modification of firmware.
•High voltage only up to 120V (requires modification from 100V nominal)
Wiener MPod-in-tunnel solution
LV in the tunnel. 1Crate per site!
HV in the counting room.
BUT: Has not been radiation
tested. This has to be done.
Personally I would like also the
HV crate in tunnel to avoid the
long cables. This will need
discussions with wiener.
COST: Not dicussed
Communciation: CAN 125kBit/s.
on cable SCEM 04.21.52.124.4
Conclusion on power supplies
• Both CAEN and Wiener are still candidates
• Wiener and CAEN need radiation tests
• Communication for CAEN has to be tested
with CAEN equipment.