ALICE DCS Workshop - 15/3/2004 G. De Cataldo, A.Franco, A.Tauro - INFN Bari - 1 The SY1527 replay delay via the OPC and the ‘SY driver’ (By HMPID) The disappointing time response for the SY1527 via OPCThe disappointing time response for the SY1527 via OPC The OPC, the CAEN Wrapper library and the ‘SY Driver’ developed by the HMPIDThe OPC, the CAEN Wrapper library and the ‘SY Driver’ developed by the HMPID Test results on the SY1527 reply delay: a comparison between the OPC and SY driversTest results on the SY1527 reply delay: a comparison between the OPC and SY drivers ConclusionsConclusions

ALICE DCS Workshop - 15/3/2004 G. De Cataldo, A.Franco, A.Tauro - INFN Bari - 2 Set up for the HMPID HV-LV control HV Sub-system LV Sub-system Ethernet CAEN A1676W  WIENER PL500F8 CAEN SY1527 CANbus PVSS - WorkstationOPC Server - Workstation CAEN A1821P The A1821P is a 12 ch HV board providing 2KV to the HMPID MWPC, while the A1676W is a CANbus controller that allows for to control up to eight WIENER PL500F8 for a total of 64 channels. So the A1676W appear to be a CAEN board with 64 channels. The Workstation for the OPC Server is a Win2000 O.S. running the OPC Servers (CAEN and Siemens). The PVSS Workstation is a Win2000 O.S. running the PVSS 2.12 – JCOP Framework and the HMPID DCS control programs. A bit of history During some HMPID beam tests (2003) a reaction time of several seconds in the operation of the HMPID HV-LV system (equipped with 12 chs) was observed. The higher the number of controlled channels the higher the reply delay. The PVSS control program was linked to the SY1527 via the CAEN OPC server.

ALICE DCS Workshop - 15/3/2004 G. De Cataldo, A.Franco, A.Tauro - INFN Bari - 3 CAEN OPC – PVSS into the HMPID DCS architecture WIENER PL500 Firmware A1676W Firmware A1821P Firmware CAEN SY-1527 Firmware (Linux – Based) CAEN SY-1527 Firmware (Linux – Based) CAEN Wrapper Windows Library CAEN Wrapper Windows Library CAEN OPC Server OPC Client Driver EVENT Manager DATA Manager USER Interface PVSS – Client Application OPC Server User Control Program User Control Program ARCHIVE Manager By means of a polling procedure, the firmware of the WINER PL500 and the A1821P collect parameter’s values from the hardware, and send them to the CAEN SY1527 firmware. At regular time intervals (about 250 ms) the CAEN OPC Server calls a series of library routines, Wrapper, that are able to query data from the SY1527. Then the OPC Server verify the changed data and at regular intervals send them to the subscribed PVSS Clients. The PVSS OPC Client notify the changed values to the PVSS EVENT Manager that dispatch them to all the active PVSS software modules and interfaces.

ALICE DCS Workshop - 15/3/2004 G. De Cataldo, A.Franco, A.Tauro - INFN Bari - 4 Improving the access to the CAEN SY1527 WIENER PL500 Firmware A1676W Firmware A1821P Firmware CAEN SY-1527 Firmware (Linux – Based) CAEN SY-1527 Firmware (Linux – Based) CAEN Wrapper Windows/Linux Library CAEN Wrapper Windows/Linux Library SY HMPID Driver EVENT Manager DATA Manager USER Interface PVSS – Client Application User Control Program User Control Program ARCHIVE Manager In order to investigate the possibility to improve the performance in the data exchange between the PVSS applications and the CAEN SY1527 crate, we develop a Custom PVSS Driver: the ‘SY Driver’ which skips the OPC. This driver is able to access the CAEN PS directly (at a programmable polling rate starting from 50 ms ), to read the data and dispatch them to the linked PVSS DataPoints. Conversely if a DP value changes (e.g. different Vset) then the new value is written in the SY1527. In order to investigate the possibility to improve the performance in the data exchange between the PVSS applications and the CAEN SY1527 crate, we develop a Custom PVSS Driver: the ‘SY Driver’ which skips the OPC. This driver is able to access the CAEN PS directly (at a programmable polling rate starting from 50 ms ), to read the data and dispatch them to the linked PVSS DataPoints. Conversely if a DP value changes (e.g. different Vset) then the new value is written in the SY1527.

ALICE DCS Workshop - 15/3/2004 G. De Cataldo, A.Franco, A.Tauro - INFN Bari - 5 Experimental setup and the Number of the OPC Items Ethernet CAEN SY1527 PVSS + SY_HMPID driver - Workstation CAEN A1821P Pentium II 800 MHz Memory : 512 MB Ethernet LAN 10MB Windows 2000 – cern settings PVSS Framework CERN cern.ch Network CERN cern.ch Network 5 Card A1821P – 12 x 5 ch. 2KV Vset=200V RUP=25 Volt/s RDW=25 Volt/s  250 ms CAEN firmware polling rate 8 sec for rumping up 32 maximum theoretical number of samples 1 Card A1676W – 3 Wiener crates 3 x 8 ch. OPC driver items x 84 Ch. ReadWriteRead onceTotal crate x board x channel x Total OPC driver items x 48 Ch. ReadWriteRead onceTotal crate x board x channel x Total OPC items x 12 Ch. ReadWriteRead onceTotal crate x board x1167 channel x Total SY-HMPID driver items x 84 Ch. ReadWriteRead onceTotal crate x board x channel x channel x Total

ALICE DCS Workshop - 15/3/2004 G. De Cataldo, A.Franco, A.Tauro - INFN Bari - 6 Comparison between OPC and SY Driver with a low number of Items In the figure above the reply delay never goes below 1.1 sec. It seems to be a pedestal value in the PVSS HMPID DCS The Polling cycle longer than 250 ms increases the Reply delay. Shorter than 250 ms it doesn’t improve the overall performances, maybe showing a system (SY1527+board) limit. The Sy1527 reply delay is on the average 199 ± 85 ms longer in the standalone OPC server configuration (grey line) with respect to the single Workstation setup(blue line). The SY-Hmpid driver shows better performances (red line) for both the Reply delay and the Number of Samples as shown also in the figure on the left. In order to compare the performances of the OPC and SY Driver we carried out some tests measuring the reply delay (the time interval between a command issue and the relevant system reply) and the number of samples during a rump up phase vs. the polling cycle time. Three different test configurations were implemented: OPC Server/ PVSS Client on a single workstation OPC Server - PVSS Client on two different Wks. SY-Hmpid driver on the PVSS machine

ALICE DCS Workshop - 15/3/2004 G. De Cataldo, A.Franco, A.Tauro - INFN Bari - 7 Reply Delay vs. number of Items Fixing the Polling time at 250 msec, we have measured the reply delay and # samples vs. the number of defined channels and, as parameter, the number of channels switched ON/OFF each time. 12 def. chs.- 12 chs switched On/Off. 48 def. chs or 48 chs. switched On/Off 84 def. chs. - 24,48,64,84 chs switched On/Off As shown in the figure on the left, with the OPC connection, the reply delay is heavily affected by the NUMBER of DEFINED channels (# of items) while it is much less sensitive to the number of channels switched ON/OFF which represents the amount of information exchanged on the connection during the system operation. The SY-Hmpid driver shows evident better performances with a reply delay of a factor 6 smaller when 84 channels are defined. The HMPID at its full configuration will control up to 159 HV-LV channels then New tests are now scheduled ,48 84,64 44,24 84,64,44, ,

ALICE DCS Workshop - 15/3/2004 G. De Cataldo, A.Franco, A.Tauro - INFN Bari - 8 Detailed statistic

ALICE DCS Workshop - 15/3/2004 G. De Cataldo, A.Franco, A.Tauro - INFN Bari - 9 SY-HMPID driver: overview Developed with the PVSS API technologyDeveloped with the PVSS API technology Portable on Linux platformsPortable on Linux platforms Configurable by an ASCII config fileConfigurable by an ASCII config file Direct access to PVSS DataPoint elementDirect access to PVSS DataPoint element Automatic downloading in PVSS from the CAEN SY1527 of the Engineering Units and Value RangeAutomatic downloading in PVSS from the CAEN SY1527 of the Engineering Units and Value Range Possibility to include into the driver Alarm Conditions with Quick Reaction procedure (reaction time  150 msec)Possibility to include into the driver Alarm Conditions with Quick Reaction procedure (reaction time  150 msec) HeartBeat variable to check the PVSS-SY1527 connectionHeartBeat variable to check the PVSS-SY1527 connection

ALICE DCS Workshop - 15/3/2004 G. De Cataldo, A.Franco, A.Tauro - INFN Bari - 10 SY-HMPID driver vs. OPC OPC Server ProsCons Standard industrial technology (Microsoft DCOM)Standard industrial technology (Microsoft DCOM) Sophisticated data items accessSophisticated data items access Software ready to useSoftware ready to use Export items to more then one network Computer/ApplicationExport items to more then one network Computer/Application Low rate of data exchangeLow rate of data exchange Windows platforms needWindows platforms need SY-HMPID driver ProsCons Linux platform migrationLinux platform migration High rate of data exchangeHigh rate of data exchange Custom solution for low reaction timeCustom solution for low reaction time No standard (only for PVSS)No standard (only for PVSS) Peer-to-peer connectionPeer-to-peer connection

ALICE DCS Workshop - 15/3/2004 G. De Cataldo, A.Franco, A.Tauro - INFN Bari - 11 CONCLUSIONS 1.During some HMPID beam tests a delay between a command issue and the SY1527 reply up to several seconds was observed in the operation of the HMPID HV-LV system (CAEN SY1527 equipped with 11 chs). The PVSS control program was linked to the SY1527 via the CAEN OPC server. 2.At the end of the last year (2003) a campaign of new tests were started to look for a faster solution. A dedicated driver, namely the ‘SY Driver’ has been developed by the HMPID group with the PVSS API technology. It connects the SY1527 directly via the CAEN Wrapper library skipping the OPC. 3.In this way, when 84 channels are controlled, the replay delay is reduced by a factor 6: from 12 s with the OPC, down to 2 s with the SY Driver. The full equipped HMPID HV-LV system gets up to 159 channels, to verify also in this case the system behavior, in the next future we are going to carry out additional tests.