ESLM 21/02/2013, Rafal Kulaga, TE-MPE-EE Hardware and software upgrade for the High Voltage Crate Rafal Kulaga, AGH UST (Krakow)

ESLM 21/02/2013, Rafal Kulaga, TE-MPE-EE Table of contents What is the High Voltage Crate and for which tests it is used Existing problems and shortcomings Goals of the upgrade Implementation details (hardware/software) Propositions for the future work 2

ESLM 21/02/2013, Rafal Kulaga, TE-MPE-EE High Voltage Crate Part of the TP4 system used for TP4-B – test of circuits powered by the DFB MIC – in the high voltage part of the test (quench heater tests) DOC – test of locally powered circuits Test voltages up to 2400 V (2000 V with old HV power supplies) 3

ESLM 21/02/2013, Rafal Kulaga, TE-MPE-EE High Voltage Crate modules 4 8 Channel modules SC HV PS PS USB DAQ

ESLM 21/02/2013, Rafal Kulaga, TE-MPE-EE Simplified electrical schematic 5 Source: HV crate user manual

ESLM 21/02/2013, Rafal Kulaga, TE-MPE-EE Old DAQ module 6 PMD 1208 SN74LS373N Latches

ESLM 21/02/2013, Rafal Kulaga, TE-MPE-EE Goals of the upgrade 7 ProblemImplemented solution No isolation between the crate and the PCDouble isolation (2.5 KV): DAQ/Backplane, PC/DAQ Crate connected to the PC using two cables: RS- 232 cable (HV power supply) and USB cable (DAQ) Connection with a single USB cable, DAQ module now controls the HV power supply No transient protection leading to unreliable operation under certain circumstances Transient protection devices used prevent disturbances even when the crate is misused; recovery methods implemented in firmware No interlocking on the firmware levelInterlocking on the level of the DAQ firmware mitigates the consequences of operator/application programmer’s mistakes No application specific commands → need for complicated host software DAQ is controlled using the set of around 40 application-specific commands Possible problems with PMD 1208 drivers for future versions of MS Windows and LabView USBTMC/USB488 drivers provided by National Instruments

ESLM 21/02/2013, Rafal Kulaga, TE-MPE-EE New DAQ module 8 MCU Env. Sensor I/O Expanders EHQ Isolation Signal Conditioning ADC DAQ/Backplane Isolation USB/DAQ Isolation PCB designed by Bruno Recordon

ESLM 21/02/2013, Rafal Kulaga, TE-MPE-EE New DAQ module 9 PCB designed by Bruno Recordon

ESLM 21/02/2013, Rafal Kulaga, TE-MPE-EE Transient protection 10 Old DAQ was unreliable when exposed to noise/transients, due to the use of PMD 1208 card and latches to hold states of 28 digital outputs Because of the nature of the applications of the HV crate, DAQ will be exposed to transients and noise, so we need to protect against them With the old DAQ, transients were conducted to the PC through the USB cable → risk of PC damage During testing, we observed that some ICs used in the new DAQ can latch-up when not protected against transients New DAQ provides double isolation and transient protection, to mitigate these problems

ESLM 21/02/2013, Rafal Kulaga, TE-MPE-EE Transient protection 11 D – TVS diode, works in avalanche mode, clamps voltage at a certain level C – works as an AC shunt to prevent undesirable energy from entering IC pins Source: ProTek Devices TA1003

ESLM 21/02/2013, Rafal Kulaga, TE-MPE-EE DAQ firmware 12 Firmware written in C, using Atmel Studio IDE → same environment was used for the development of the TP4 system Firmware uses Atmel Software Framework libraries to simplify use of timers, watchdog, I2C and USB controller Divided into modules:

ESLM 21/02/2013, Rafal Kulaga, TE-MPE-EE PC/DAQ communication 13 DAQ communicates with the PC using USBTMC device class Some features of the USB488 subclass are also implemented (service requests) Drivers available for MS Windows (NI VISA – Virtual Instrument Software Architecture), GNU/Linux distributions (usbtmc kernel module and a version provided by Agilent Technologies), OS X (NI VISA) ViStatus viOpen (ViSession sesn, ViRsrc name, ViAccessMode mode, ViUInt32 timeout, ViPSession vi); ViStatus viWrite (ViSession vi, ViBuf buf, ViUInt32 cnt, ViPUInt32 retCnt); ViStatus viRead (ViSession vi, ViPBuf buf, ViUInt32 cnt, ViPUInt32 retCnt); ViStatus viClose (ViObject vi); Using VISA devices in LabView Excerpt of the C API for VISA

ESLM 21/02/2013, Rafal Kulaga, TE-MPE-EE USBTMC/USB488 device classes 14 Simple query/answer protocol More and more popular for test&measurement devices with USB interfaces (along with USB CDC and HID) Implementation of the USBTMC/USB488 device classes can be used for different systems

ESLM 21/02/2013, Rafal Kulaga, TE-MPE-EE DAQ firmware - continued 15 Command begins with : Command begins with * DEV_DEP_MSG_OUT REQUEST_DEV_DEP_MSG_IN

ESLM 21/02/2013, Rafal Kulaga, TE-MPE-EE Command set 16 Around 40 commands divided into groups (SCPI-like) :HVSOURCE :HVSOURCE:VOLTAGE? :HVSOURCE:VOLTAGE:SETPOINT :THSENSOR :THSENSOR:TEMPERATURE? :CHANNEL :CHANNEL:VOLTAGE :MEASUREMENT :MEASUREMENT:MODE :MEASUREMENT:RATE? :MEASUREMENT:GET :SYSTEM :SYSTEM:NAME Some standard SCPI commands: *IDN?, *RST

ESLM 21/02/2013, Rafal Kulaga, TE-MPE-EE Proposals for future work 17 Current design of the HV crate is around 8 years old, so it will need some attention in the future Communication between modules via parallel GPIO lines → extensions not possible, complicated backplane design Ineffective power supply – many redundant DC/DC converters used

ESLM 21/02/2013, Rafal Kulaga, TE-MPE-EE Proposals for future work 18 Redesign all the modules: backplane, 8-channel modules, signal conditioner and power supply Use I2C or CAN bus for communication between modules → simplified PCB design Streamline power supply by eliminating redundant DC/DC converters Redesign the PCB in a way that reduces EMC-related problems

ESLM 21/02/2013, Rafal Kulaga, TE-MPE-EE Summary 19 Using new DAQ provides following benefits: Simplified connection to the PC and simple programming interface Reliable operation even when safety procedures are not duly followed by an operator Isolation between the PC and HV crate More accurate measurements Implementation of the USBTMC/USB488 device class can be used in other systems (possibly TP4) → unified communication Firmware upgrade through USB connection thanks to DFU (Device Firmware Upgrade) bootloader Status: Hardware tested and ready for production Upgrade plan for the systems needs to be developed

ESLM 21/02/2013, Rafal Kulaga, TE-MPE-EE Acknowledgements 20 Thanks to: Mateusz Bednarek and Jaromir Ludwin for important remarks on the hardware and software design Bruno Recordon for his great work on the PCB layout design

ESLM 21/02/2013, Rafal Kulaga, TE-MPE-EE Thank you for your attention!