1. ATLAS DCS ELMB PRR, CERN, March 2002Fernando Varela ELMB Networks CAN/CANopen Interoperability of the ELMB Usage of the ELMB in ATLAS ELMB Networks Full Branch Test Conclusions Future work Outline

2. ATLAS DCS ELMB PRR, CERN, March 2002Fernando Varela 120  Beckhoff Wago Compliance of the ELMB

3. ATLAS DCS ELMB PRR, CERN, March 2002Fernando Varela Aims of the Test: TileCal Cooling and LV: 8 ELMBs Pixel Cooling: 7 ELMBs COMPASS 10 ELMBS Currently Pixel Cooling : 12 ELMBs MDT 10 ELMBs COMPASS 16 ELMBs Next Year 5000 ELMBs in ATLAS – 1200 MDT (test case, should cover all subdetectors) – 1000 RPC – 800 TGC ATLAS Powering Performance: tuning of parameters identifying bottlenecks 50 mm 66 mm Reliability Robustness Definition of recovery procedures Usage of the ELMB >> Give guidelines and recommendations to set up ELMB networks in ATLAS <<

4. ATLAS DCS ELMB PRR, CERN, March 2002Fernando Varela The maximum number of ELMBs per bus is 64 for addressing reasons (6 bits), i.e. 4096 Analog Inputs However, the number of ELMBs per branch must be a compromise: – Cost; a higher number of ELMB modules per bus => a lower number of buses and PCs – Affordable number of channels to be lost in case of a branch failure. – Performance and reliability of the readout system. – Powering of the CAN network (PS placed in USA15). 120  Branch_1 Branch_2 ELMB Networks

5. ATLAS DCS ELMB PRR, CERN, March 2002Fernando Varela SCX1 USA15 Front-End System Back-End System Local Area Network Partition 3 Supervisory only Partition m UX15 Partition 2 Common Infrastructure Local Control Stations (LCS) Partition 1 Expert Workstations ServerOperation Subdetector 1Subdetector 2a Subdetector n Detector Sub-system Sensors Actuators Fieldbus 200m  ELMB Electronic Rack ELMB Rack PC Power Supply Cooling Interlock Box Test Rack PC ELMB Alarms CFS HV Barrel Architecture of DCS

6. ATLAS DCS ELMB PRR, CERN, March 2002Fernando Varela ELMB Full Branch Test

7. ATLAS DCS ELMB PRR, CERN, March 2002Fernando Varela ELMB ELMB Full Branch Test

8. ATLAS DCS ELMB PRR, CERN, March 2002Fernando Varela ELMB ELMB Full Branch Test

9. ATLAS DCS ELMB PRR, CERN, March 2002Fernando Varela Set Up Only one PS used. Digital and CAN parts of the ELMB and NI-CAN card powered via the bus. Analogue part powered from the digital (Power monitored by a scope). Normally powered from the FE equipment Bus and Interface card power lines were de-coupled (Allows for independent reset of both elements). 120  0x3F0x30 CANbus 200 m 16 V PS LCS 120  D9 Connectors Powering

10. ATLAS DCS ELMB PRR, CERN, March 2002Fernando Varela 16 x 8 = 128 digital input lines (Sync + Async), 16 x 2 x 8 = 256 digital output lines (Async) Input and output lines interconnected 16 x 64 = 1024 Analogue channels (Sync) ELMBs reprogrammed to bypass filtering in OPC server and ensure maximum data volume transfer to PVSS-II (Worst possible case) ELMB I/O Functionality t SYNC_1 ELMB_30ELMB_31ELMB_3F  ELMB_30_0ELMB_31_0   ELMB_3F_0 SYNC_2 ELMB_30 SYNC Interval... ELMB_30_1 ELMB_31_1 ...  Digital Signals (Higher Priority) Analogue Channels (Lower Priority) ELMB_3F_1ELMB_3F_63 Bus Cycle... If adc = 32.5 Hz and Bus Speed = 125 kbit/s  ~ 0.8 ms => Time difference between messages on the bus;  ~ 30.8 ms => Time needed for ADC conversion

11. ATLAS DCS ELMB PRR, CERN, March 2002Fernando Varela CAN Analyzer Diagnostic Tool SYNC Digital Signals Analogue Channels Bus load No. of CAN frames

12. ATLAS DCS ELMB PRR, CERN, March 2002Fernando Varela Bus Load

13. ATLAS DCS ELMB PRR, CERN, March 2002Fernando Varela Performance

14. ATLAS DCS ELMB PRR, CERN, March 2002Fernando Varela Data get lost at higher data rates when SYNC Interval -> bus cycle Bottlenecks: NI CAN interface card (buffer overflow) => Need for a new interface (cost and characteristics). PVSS archiving (CPU consumption) => Better distribution of the tasks performed by SCADA. Performance (II)

15. ATLAS DCS ELMB PRR, CERN, March 2002Fernando Varela Comparison at different Bus Speeds Results shown at 125 kbits/s were reproduced, i.e. 100 % transfer rate for a bus having 16 ELMBs and SYNC Interval equal to 4 s.

16. ATLAS DCS ELMB PRR, CERN, March 2002Fernando Varela 200 m long ELMB Branch with up to 16 nodes successfully operated. I/O channels of the order of magnitude of some subdetectors in ATLAS: 1024 AI, 256 DO, 128 DI Preliminary studies of the powering has been carried out. The test tried to reproduce the “worst possible case” => All ELMBs transmitting at the same time. The system has shown excellent performance:Transfer rate of 100% for messages of different priorities on the bus and of different transmission types. Maximum readout rate 4s at 32.5 Hz. Results are reproducible at 250 kbits/s => Less bus load (but also smaller bus length). Several issues were identified at higher adc when SYNC  Bus Cycle Overflows in the read buffer of the NI-CAN interface Strange behavior of PVSS-II manager as a function of the OPC update rate. High CPU consumption by the PVSS archiving manager However, the CANalyzer showed the correct operation of all ELMBs on the bus. Conclusions

17. ATLAS DCS ELMB PRR, CERN, March 2002Fernando Varela Optimize powering of the bus => minimize voltage drop in the CANbus cable. Window-checking in the ELMB. Increase number of ELMBs up to 32 or 64. Several buses per PC. Test of network supervision and management -> Definition of error recovery procedures Long-term operability of the system in TCC2. Automatic power cycle of the bus needed due to SEEs (see below). Future Work