MSPI-16(Data sheet V1.0_01),Eventbus to Parallel
Interface andRemote Controller

mesytec MSPI-16 is a parallel data interface and controller unit for neutron detector
readout electronics. Frontend devices are connected over the highspeed serial event bus.
It provides the possibility to control all internal settings of the connected modules. It
interfaces up to 16 MPDS-8+ via point to point connection on 16 eventbus branches to aparallel output for external data acquisition systems and histogrammers. Data arepresented buffered (256 events buffer). Basic features of the connected modules likepulser test and amplitude/position mode can be controlled via front panel elements. The
RS-232 and USB interfaces allow detailed setup of all parameters of the connected
frontend electronics. Up to 128 position sensitive detector tubes can be handled with one
module.

Features:• 16 high speed event buses• Up to 16 MPSD-8+= up to 128 position sensitive detectors• Front panel control allows quick test
routines and mode selection• Full remote control (RS-232 / USB) for all
MSPI-16 and MPSD-8+ parameters• Buffered parallel data output for external
histogramming

mesytec GmbH & Co. KG
Wernher-von-Braun-Str. 1, D-85640 Putzbrunn, Germany
phone: +49 – 89 / 456007-30 fax: +49 – 89 / 456007-39
info@mesytec.com – www.mesytec.com

MSPI-16

Setup:

Parallel Eventbus Interface

Init

Bus Connection

All frontend modules are connected via the serial
event bus over point to point connections. Bus
medium is a standard RG174 coaxial cable.
A total of 16 modules (MPSD-8+ or MSTD-16)
can be connected with the MSPI.

Pressing the init button for more than 1 secondstarts a re-initialisation of all connected frontend
modules, using the saved configuration.
Event buses, indicators

Status LEDs show activity and errors on theeventbus, one for each possible device address.

Adressing

Remote control operation

Each frontend electronic module is addressed by
the bus number (0...15) used for connection.

Remote control over the RS-232 or the USB
interface allows detailed settings for eachindividual channel (gains) or module (threshold),
as well as for the integrated test pulser. Saved
setup is downloaded to connected peripheraldevices on power up and by pushing the “init”button.

Operation:
Frontpanel operation

Basic features of the frontend electronics can bedirectly accessed by frontpanel elements:• Operating mode (Position/Amplitude)• Initialization• Pulser test

Interface setting

Modes

USB:
using the FTDI generic comport driver allows
communication live over a serial com port. Up todata drivers for most common operating systems
can be found at:
http://www.ftdichip.com/FTDriver.htm

There are two modes for MPSD-8 modules which
can be toggled by a pushbutton:• Position mode (default setting):
data represent the calculated 10 bit position.
This is the mode for position resolved neutronmeasurements.
• Amplitude mode:
data represent 10 bit amplitude signals.
Useful for diagnosis and detailed setup of HV,gain and threshold.
Position mode is the power up default mode.
PulserMPSD-8+ have integrated test pulsers fordiagnosis. They can be activated by a pushbutton
at the MSPI-16. The pulser cycles through allconnected channels in left / middle / right position(in position mode) or high / medium amplitude.
This allows an easy check for electronic
functionality.

RS-232: 9600 Bd., 8N1(eight data bist, no parity, one stop bit)Command set

The following command set is used to control theparameters of the connected MPSD-8+ or
MSTD-16. Just enter the commands in a terminal
window with a serial connection to the MSPI.
Generaladdr

module address = bus number[0...15, 16 = all]chanchannel number[0...7, 8 = all]value

nummerical value to be settable<CR>

menas the <carriage return> or<enter> key

mesytec GmbH & Co. KG
Wernher-von-Braun-Str. 1, D-85640 Putzbrunn, Germany
phone: +49 – 89 / 456007-30 fax: +49 – 89 / 456007-39
info@mesytec.com – www.mesytec.com

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MSPI-16

Parallel Eventbus Interface

Commands:General?
HDS

Typical Examples

list available commands / “Help”
display status

MSPI-16 commands

MPswitch to position modeMAswitch to amplitude (energy)
mode

DO valAt power on, the MSPI-16 should be in areasonable status, checking all connected
peripheral devices and initializing them to setup
values saved in memory.
(Which are reasonable defaults if not changed.)
Adjusting threshold

TH 0 25

set data offset to val [0...63],
default = 32

sets threshold for the moduleconnected on bus 0 to numericalvalue 25

TH 8 25

sets threshold for all connected
modules to numerical value 25

PTstart/stop pulser test

Adjusting gain

D1D0

start data acquisition
stop data acquisition

GA 0 0 120

MPSD-8+ commands
GA addr chan val set gain for module addr
and channel chan to val[0...255], default = 128

sets gain for channel 0 of
the module connected on
bus 0 to numericalvalue 120

GA 0 8 120

set common threshold formodule addr to val[0...255], default = 20

sets gain for all channelsof the module connectedon bus 0 to numericalvalue 120

GA 16 8 120

set pulser amplitude formodule addr to val[0...255]

sets gain for all channelsof all connected modules
to numerical value 120

Using the test pulser

TH addr val

PA addr val

PP addr chan pos

P1 addr
P0 addrset pulser position formodule addr to chan andpos [l, m, r]
switch pulser in module
addr onswitch pulser in module
addr off

RI addrread device ID of module
addr (return s 0 if notconnected)

IN addrinitialize module addr
(dump saved settings)

PA 0 80

sets pulser amplitude of themodule connected on bus 0 tonumerical value 80

PP 0 4 m

sets pulser position of the moduleconnected on bus 0 to channel 4,middle

P1 0switches pulser of the moduleconnected on bus 0 on

mesytec GmbH & Co. KG
Wernher-von-Braun-Str. 1, D-85640 Putzbrunn, Germany
phone: +49 – 89 / 456007-30 fax: +49 – 89 / 456007-39
info@mesytec.com – www.mesytec.com

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MSPI-16

Quick start:
For a first look on the operation of MSPI-16
together with MPSD-8+, proceed like follows:
Connect MSPI-16 and MPSD-8+ with theevent bus cable• Press “Init” at the MSPI-16, default
initialisation is sent to MPSD-8+• Click “Pulser” at the MSPI-16 Eventbus LEDs
should now show activity at MSPI-16 andMPSD-8+. Data are output at the Sub-D 25
parallel port.
•Data output format:
MSPI presents the following signals at its
parallel data interfaces

Parallel Eventbus Interface• Change MSPI-16 to amplitude mode(either with frontpanel pushbutton or with rccommand ”MA”)• Ramp detector bias voltage to estimated value.
• Check the resulting amplitude spectrum andadjust bias voltage. The thermal peak positionof the amplitude spectrum should be shifted toabout 80 % of maximum range.
• Set threshold accordingly to cut off the gamma
tail in the lower part of the spectrum using therc command “TH”
• If necessary, adjust individual channel gains
using the rc command “GA”
Data transfer rate

• 4 bit bus (module) address (M0...M3)• 4 bit channel address (C0...C3)
for MPSD-8+: C3 = position/amplitude mode)• 10 bit conversion data (amplitude/position)• strobe for data ready (active low)

Mean transfer rate 1.6 MHz at 20 % deadtime(100 kHz per serial bus), 5 MHz maximum rate.
For higher rates the system can be parallelized.
Parallel output transmit cycle

Parallel interface• Eight bit address(higher nibble: bus number,lower nibble: channel)• 10 bit conversion data (P0...P9)(P = Position, A = Amplitude/Energy)
Name

A7

A6A5A4A3A2A1A0

Comment M3M2M1M0C3C2C1C0MSPI pin2019618517416Name

D9 D8 D7 D6 D5 D4 D3 D2 D1 D0

CommentP/A P/A P/A P/A P/A P/A P/A P/A P/A P/A54321MSPI pin

24 11 23 10 22921825 12Name

L (strobe)

gndgndgnd

9876gnd

02Data valid 75 ns before strobe goes nagative,
until50 ns after rising edge of strobe.
Strobe length: 75 ns / Full transmit cycle: 200 ns

Technical Data:
Power consumption

Comment 75 ns pulse
MSPI pinblue: data line, yellow: L-strobe signal

1713Detailed setup

A more detailed electronics setup of a 3He psd
detector system can be performed with thefollowing steps:+6 V: 230 mA
–6 V:
30 mA
total:
1.6 W
Size:

overall size 800 x 222 x 34 mm(1/12 NIM case)
Weight: 980 g

mesytec GmbH & Co. KG
Wernher-von-Braun-Str. 1, D-85640 Putzbrunn, Germany
phone: +49 – 89 / 456007-30 fax: +49 – 89 / 456007-39
info@mesytec.com – www.mesytec.com

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