Slow Controls for Production Silicon Vertex Tracker Modules
A slow controls system (SCS) will be used for the Hybrid Flex Circuit Board (HFCB)
test stand and the module burn-in test stand. The SCS will consist of a Weiner MPOD
mainframe, Weiner low voltage modules, ISEG high voltage modules, Fig. 1, a Windows-based
PC running the LabVIEW production software (LPS), National Instruments Compact Rio (cRIO)
hardware, and temperature/humidity sensors.
FIG. 1. Wiener MPOD, Wiener low voltage module, and ISEG high voltage module.
1. LabVIEW Production Software and Hardware
The LPS is capable of controlling and monitoring four SVT modules at once, through the
MPOD controller via Ethernet. The purpose of the LPS is to monitor voltage, current,
temperature, humidity, and condensation of the modules being tested, and in the case of system
failure, react before damage can occur to an SVT module.
During SVT module testing, damage to a module can occur when low voltage or high
voltage goes over voltage or over current. When the LPS is started, it reads a configuration file
set by the user and then sets voltage and current trip limits for the MPOD’s low voltage and high
voltage modules. If one of these limits is met or exceeded by a channel, that channel is
immediately turned off by the MPOD. As a backup to the MPOD, the LPS also monitors the
voltages and currents for an over-voltage or over-current situation. If either the MPOD or LPS
detect a met or exceeded limit, the user is notified by a LabVIEW front panel indicator, Fig. 2,
and automatic action is taken to shut down the malfunctioning channel.
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FIG. 2. LPS Front Panel GUI. The front panel is divided into four section representing four SVT modules. Green
indicators indicate no failures. Red indicators represent a failure.
Heat can also damage a module. The LPS has the capability of measuring temperature in
two ways, directly on the module and ambient temperature.
There are two temperature sensors located on the HFCB, one sensor on each side of the
HFCB, between the two FSSR2 ASICs. Each temperature sensor outputs a voltage that is read
by a cRIO 9215 ADC module, located in a cRIO 9075 chassis, Fig. 3. The cRIO chassis
communicates the voltage read by the ADC via Ethernet to the LPS. The LPS then takes this
voltage and converts it to a temperature in C°. If an over-temperature situation is detected, the
LPS immediately turns off low voltage and high voltage to the respective side of the SVT
module. The user is then notified by an indicator on the LPS front panel.
FIG. 3. NI cRIO 9075 chassis, cRIO 9215 ADC module, cRIO 9217 RTD module, and cRIO 9481 relay module.
Ambient temperature is measured by an external RTD, which is placed within a few feet
of the SVT modules being tested. The sensor communicates with a cRIO 9217 RTD module,
FIG. 3, located in the cRIO chassis, which then communicates with the LPS. If an overtemperature is detected by the LPS, all low voltage and high voltage to the SVT modules being
tested are turned off. The user is notified by an indicator on the LPS front panel.
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Humidity adversely affects the SVT module being tested. A humidity sensor is placed
within a few feet of SVT modules being tested. The humidity sensor outputs a voltage, which in
turn is read by the ADC in the cRIO chassis, and then sent by the chassis to the LPS. This
voltage is converted to a humidity in per cent by the LPS. If an over- or under-humidity
situation is detected, the LPS turns off all low voltage and high voltage to the SVT modules
being tested. The user is then notified by an indicator on the LPS front panel.
Condensation can also damage SVT modules during testing. Using the ambient
temperature sensor and the humidity sensor, a dew point can be calculated using the following
formulas.
Eq. 1: Saturation Vapor Pressure ( Tc is temperature in C); Es  6.11  10.0
Eq. 2: Actual Vapor Pressure (RH is relative humidity in %); E 
Eq. 3: Dew Point Temp in C.; Tdc 
 7.5Tc 


 237.7 Tc 
 RH  Es 
100
 430.22  237.7  ln( E ) 
  ln( E )  19.08
The calculated dew point temperature (DPT) is compared to the temperature sensor reading from
the HFCB. If it is within 5°C of the DPT, then the chiller cooling the modules is shut down by
the cRIO 9481 Relay module, Fig. 3, located in the cRIO chassis. The user is then notified of the
dew point by the dew point indicator on the LPS front panel. If corrective action is not taken by
the user, the SVT modules’ HFCB temperature sensor will continue to be monitored. When the
modules have reached ~10°C above room temperature, the low voltage and high voltage will be
turned off.
The LPS also monitors for under-voltage and under-current. Under-voltage and undercurrent situations will not damage the SVT modules being tested, but are an indicator of a
problem with SVT module(s) being tested. If an under-voltage or under-current situation is
detected, the user is notified by an indicator on the LPS front panel. (See Appendix for fault
chart.)
While monitoring, all values are recorded in a text file, which is time-stamped and placed
into a database. A LabVIEW program to plot this data has been created. This allows the user,
should an issue arise with a SVT module during production, to examine the data quickly,
accelerating the troubleshooting process.
2. FermiLab Burn-In Test Stand
The burn-in test stand is used to control and monitor, for at least 24 hours, four fullyassembled, fully-powered SVT modules at one time. Burn-in is done at FermiLab since only
minor repairs can be made at Jefferson Lab to SVT modules.
The burn-in test stand’s SCS will consist of a control PC running the LPS, one MPOD
mainframe, two low voltage modules, one high voltage module, and a cRIO chassis. The cRIO
chassis will contain two ADC modules, one RTD module and one relay module. The two ADC
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modules will handle readback from the HFCB temperature sensors. The RTD module will
handle readback from the ambient temperature sensor and the relay module will control power to
the chiller, Fig. 5.
FIG. 5. Arrangement of cRIO modules and channels in the cRIO chassis for the burn in test stand.
The cRIO chassis is only capable of holding four cRIO modules. This doesn’t allow for a
humidity sensor, which is critical to the burn-in test stand. This is circumvented by sharing
resources with the HFCB test stand and will be addressed in the next section.
All functions of the LPS described in the previous section will be used during the burn-in
test of the SVT modules.
3. HFCB Test Stand
Before an SVT module is fully assembled, it is tested at various stages during the assembly
process. The HFCB test stand’s SCS will handle control and monitoring of three HFCB modules
at these various stages, as well as lend its resources to the burn-in test stand. The HFCB test
stand’s SCS will use the same PC running the LPS as the burn-in test stand, an MPOD
mainframe containing two low voltage modules, one high voltage module, and a cRIO chassis.
The cRIO chassis will contain two ADC modules and one RTD module. Since two ADC
channels will be available, these will be used for readback of a humidity sensor for the burn-in
test stand and a back-up humidity sensor, Fig. 6.
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FIG 6. Arrangement of cRIO modules and channels in the cRIO chassis for the HFCB test stand.
All software and hardware being used for the burn-in test stand and HFCB test stand has
been used in various individual test stands, the cosmic test stand, the gamma source test stand,
and in the M1/M2 beam test at Jefferson Lab. If hardware fails during production, spares are
available at Jefferson Lab and all items are “off-the-shelf” so that they can be received within a
week.
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Appendix A Hardware Fault Chart
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