WYFFOS - Wide Field Fibre Optic Spectograph
The WYFFOS intrument control electronics consists four sub-racks which
are housed in a 19 inch rack enclosure in the GHRIL control room. The four
The control electronics connects to the instrument via a number of cables
to each of the assemblies that have electronic controls or monitoring which
Each of the assemblies has a number of connectors that group the signals
accoring to their functions.
All the signals from the sub-assemblies connect to the Lemo interface
unit, here they are re-distributed to the relevant VME port or to the LIMPIT.
The Lemo Interface unit also contains a power supply and the signal conditioning
amplifiers for the LVDT position encoders.
The VME controller is a 7U 19 inch sub-rack with a full 84HP wide 6U VME
backplane and power supply. The extra 1U is taken up by a fixed fax tray.
The proccesor card used is a Motorola MV147S-1 with an MVME712M transition
module providing four RS232 ports an Ethernet connection, a printer port
and a SCSI interface. The VME also includes 5 I/O boards
An EPICS Database Index can be found here.
OMS8 Stepper Motor Controller
This provides 8 axis each independantly controllerable. Each axis has a
step and direction output to drive the motor and has positive and negative
limit inputs to provide hareware limits of movement. A datum input is also
provided which can be used to move the motor to a known position to check
calibration of the encoder. All connections are made via the P2 connector
on the VME backplane.
XVME 240 Digital Input/Output (DIO)
Each card provides 8 ports of TTL level digital input/output. Each port,consisting
of 8 bits can be configured to either input or output but in our application
ports 0 to 3 (Connector JK1 on the front panel) are used for inputs and
ports 4 to 7 (Connector JK2 on the front panel) are used for outputs.
XVME 220 Digital Output (DOUT)
This card provides 32 channels of opto-coupled digital output. Each channel
has a positive and negative connection so all channels are completely isolated.
Channels 0 to 15 a via JK1 on the front panel and channels 16 to 31 are
XVME 566 Fast Analogue Input (FAIN)
This card is capable of providing 16 channels of single ended 12-bit analogue
to digital converstion or as in the WYFFOS application 11 channels of double
ended 12-bit analogue to digital converstion.
Comparison Lamp Controller
The unit currently fitted The Alternative Comparison Lamp Controller is
a 2U high 19 inch mains distribution panel providing three standard mains
sockets which can be turned on and off and a status returned via a digital
interface. Each socket is controlled via a solid-state relay and provides
240V 50Hz ??amps. The control interface is via a 25 way ‘D’ connector on
the backpanel and is designed to be equivalent the interface on the comparison
lamp controllers used on ISIS and UES with the exception of and extra +5V
supply required on pin 12 of the connector which is unused on the ISIS/UES
interface which means the alternative controller will not work in place
on the standard controller (without the addition of the extra 5V supply)
but the ISIS/UES controller will work in place of the Alternative Controller.
A full description of the contrller can be found in the Alternative
Comparison Lamp Controller Technical Manual
The back panel of the limpit provides an interface to the VME8 stepper
motor controller via a 64 way DIN41612 connector and provides a motor (15
way D) and a limit (9 way D) connector for each of the 5 motor axes used.
There are also connections for the fibre back illumination (9 way D) and
a serial (9 way D) and a parallel (25 way D) connection for the grating
encoder. The limpit contains five single eurocard circuits and three power
supplies in a 3U 19 inch sub-rack. The three power supplies are Vero types
supplying +5V +12V and +24V. The five eurocards are:
D225 - Begher Lahr 5 phase stepper motor drive card
SMD4 - RGO designed and built 3 axis 4 phase stepper
DC Motor Driver - RGO designed and built circuit interfacing
a DC motor to a stepper motor controller
Fibre Back Illumination Driver - RGO designed and built
driver for the back illumination LEDS
SPEC - RGO deisgned and built serial to parallel encoder
D225 5 Phase Stepper Motor Drive Card
This is a commerically available drive card designed specifically to drive
the Begher Lahr 5 phase stepper motors. It is the same drive card as used
in the Prime Focus Instrument Platform (PFIP) Limpit. The card has 4 inputs
Step, Direction, Half/Full and an Enable and produces the drive currents
required to move the stepper motor.
SMD4 3 axis 4 Phase Stepper Motor Drive Card
This card is an RGO designed and built card and provides three independant
drives for 4 phase stepper motors. It has the same inputs as the 5 phase
stepper motor drive card for each of the three axis (Step, Direction, Half/Full
A full description of the circuit can be found in the SMD4
3 Axis 4 Phase Stepper Motor Drive Card Technical Manual
DC Motor Drive Card
This is an RGO designed and built card. It has a similar interface as the
other drive cards (Step, Direction, and Enable) but drives a DC motor using
a commercial four quadrant linear output motor driver (RS 715-005). A monostable
is retriggered on each rising edge of the step input and the output is
used as the drive request for the DC motor driver. Therefor the motor is
driven all the time the step input is clocking fast enough to stop the
monostable from timing out. However varying the step rate above this frequency
does not affect the speed of the motor, this is set by a pot on the driver
A full description of the circuit can be found in the Slit
Translation DC Motor Driver Technical Manual
Fibre Back Illumination Driver
This is an RGO designed and built card. The circuit is specifically designed
to drive the fourteen high output infra-red emmiters used to back illuminate
the WYFFOS fibres. Two 15V DC to DC converters are used to supply the 30V
required to drive the emmiters and cooling fan. A status is also returned
to verify that current is flowing through the array.
SPEC - Serial to Parallel Encoder Converter
This is an RGO designed and built Card. The device used to encode the angle
of the grating (ROC417) produces a serial output. To avoid the problems
of ensuring the VME controller could poll the encoder at the required rate
to read the serial data and convert it into a parallel word a separate
card was designed and built. The card has one input to request a new word
to be read from the encoder. When this request is set the seventeen position
bits and the parity bit are read from the encoder and put through a shift
register to produce a parallel word that can be read by the VME controller.
A conversion complete bit is set to indicate that the new word is ready
to be read.
Lemo Interface Unit
The main function of this unit is re-distribute the signals from the instrument
to the correct VME I/O or to the limpit.