Development of a Linuxbased smallsize controller using PoE technology

1
Development of a Linux-based small-size
controller using PoE technology

• T. Masuda, T. Fukui, R. Tanaka
• SPring-8
• ICALEPCS2005, Oct. 10-14, Geneva, Switzerland

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Contents

• Motivation
• PoE technology
• Development of new controller
• CPU card
• I/O cards
• Software
• Temperature measurement using new controller
• Installation plans
• Summary

3
Motivation

• We need temperature measurements in the
  accelerator buildings at many points in SPring-8.
• Investigate correlation between
• temperature and orbit distortion of electron
  beams.

4
Motivation (contd)

• Generally, we have to handle signals scattered
  around a large facility site.
• Temperature,
• Humidity,
• Total number becomes large.
• But a few signals at each place.
• How should we handle these signals?

5
Motivation (contd)

• How about VME or PC?
• gt
• It is not cost-effective to install VME or PC for
  each place.
• VME or PC are too much.

6
Motivation (contd)

• How about off-the-shelf, network-based dedicated
  devices?

Temperature and humidity measurement instrument
Ether-to-GPIB controller
These devices provide easy start-up, but
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Motivation (contd)

• Unstable
• We needed 1 year to fix the firmware bug by a
  company.
• We had to go over there to reset when it hung up.
• We needed protocol conversions to fit the
  framework.
• gt We need more flexible and stable controllers.

8
New controller

• Small size
• Linux support
• Various I/O cards available
• Temperature measurement card
• GP-IB controller card
• Power over Ethernet support
• No AC power lines
• No AC adaptors

130mm
100mm
30mm
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PoE technology
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What is Power over Ethernet?
AC power line
Legacy HUB
Before PoE
Network device
power
Ethernet cable
data
AC adapter
Network devices demand AC power lines in addition
to Ethernet cables.
AC power line
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What is Power over Ethernet?
AC power line
PoE HUB
After PoE
PoE Network device
power
Ethernet cable
data
PoE network devices can receive power from
Ethernet cables as well as data.
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What is PoE? (contd)

• IEEE standard 802.3af (June 2003)
• Extension to the existing Ethernet standards.
• gt We can mix PoE devices and non-PoE devices
  together.

PoE HUB
Non-PoE device
PoE device
AC power line
power
power
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The PoE standard

• Power Sourcing Equipment (PSE)
• Output voltage 48V DC (typ.)
• Max. output power 15.4W / 1port

PSE
power
PD
power
PD
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The PoE standard (contd)
While a PD is not connected, PSE does not apply
voltage to the cables.
PSE
x
PD
x
PD
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The PoE standard (contd)
PSE
PD
PD
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The PoE standard (contd)
PSE detects absence of the PD, then PSE stops
power.
PSE
x
x
PD
The PoE provides safer operation of the power.
PD
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Management tools for PSE

• By using this tool,
• We can control power supplying.
• We can monitor power sourcing status.

If you want to turn off the power to port 1,
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Management tools for PSE
Select port number
push set button
Select power supplying status
We can monitor the status changes of the port 1.
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Management tools for PSE
We dont need to rush there to reset the device
when the device hangs up.
We can reset the connected device remotely.
We can monitor the status change of the port 1.
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Development of new controller
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CPU card

• CPU 240MHz SH-4
• Original architecture by Hitachi
• 32bit RISC CPU with MMU
• Low power consumption
• PCI I/F for an I/O card
• Extendable for new I/O card
• 64MB SDRAM
• 32MB Flash Memory
• 10/100baseT/Tx Ethernet I/F with PoE
• USB 2.0

120mm
92mm
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Temperature measurement card

• 4-channel inputs of 3-wire Pt100 RTD sensors
• Measurement range -2080C
• Accuracy 0.1C
• Resolution 0.001C

120mm

• 4-channel 20-bit ??? A/D converter
• Full scale error 4ppm of Vref 2.5V (typ.)
• 50Hz/60Hz notch filter

92mm
RTD Resistance Temperature Detector
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Temperature measurement instrument

• Assembled from the CPU card and the temperature
  measurement card.
• Combined with a dedicated PCI connector.
• Power consumption 3.7W (typ.)

Typical assembly of the temperature measurement
instrument
CPU card
Temperature measurement card
Dedicated PCI connector
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GP-IB controller

• Assembled from the CPU card and the GP-IB
  controller card.
• Power consumption 4.1W (typ.)

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Software

• We ported SH-Linux 2.4.14 to the CPU card.
• We developed device drivers for the I/O cards.
• We introduced disk-less Linux system.
• The system has root file system on an NFS server.
  
• Any of control software (TANGO, EPICS, ) will
  work.
• We ported RPC server software of the MADOCA
  framework.

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Temperature measurement using new controller

• Can we use the PoE technology for precise
  measurement system?
• Can it work with a shielded twisted pair (STP)
  cable?
• Is voltage drop by a long Ethernet cable a
  problem?
• gt We tested.

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Measurement system
PSE
Temperature measurement instrument
5m-long STP cable
Sampling rate 1Hz
100m-long STP cable
99.950W high-precision resistance for
reference. stability 5ppm/1C
Equivalent to -0.128C in a Pt100 sensor
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Result

• The instrument worked well with a STP cable.
• Overall accuracy of 0.1C was achieved.
• agreed with the expected value ( -0.128 C).
• errors lt 0.002 C
• Voltage drop by a long Ethernet cable did not
  affect the measured value.

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Installation plans- Temperature measurement
instrument

• Install into the SCSS prototype accelerator.
• Measurement of air and wall temperatures of the
  machine tunnel.
• Install into the machine tunnel with radiation
  protection boxes.
• Because of low heat generation and PoE support.
• gt
• Reduce the wiring of Pt100 sensors.
• Enhance the measurement accuracy.

SCSS SPring-8 Compact SASE Source
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Installation plans- GP-IB controller

• Replace VME GP-IB boards.
• Because the GP-IB board makes troubles on the
  VMEbus.
• Replace the off-the-shelf dedicated GP-IB
  controllers.

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Summary

• We succeeded in developing the new Linux-based
  small-size controllers using PoE.
• PoE maximizes degree of freedom of the
  installation without AC power lines.
• PoE enhances controllability of the distributed
  controllers by using PSE management tool.
• We can apply PoE technology to precise analog
  measurement as well as digital devices.

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Thank you for your attention.