Optoscan monochromator external control interface

'D' Connector Technical Specification

This control interface is implemented via 37 way 'D' connector located on the rear panel of the system box. It gives access to a variety of logic level control inputs and outputs, as well as a number of timing signals and analogue control voltages

All logic signals are TTL, implemented in 74HC(T) series CMOS chips, i.e. low = 0V, high = +5V.


Pin Assignment

Pin
Number		 Signal description Note
1 DAC output to input slit galvo drive  
20 DAC output to grating galvo drive  
2 DAC output to output slit galvo drive  
21 User DAC output 1
3 Auxilliary "ready" input 2
22 Reserved logic output 3
4 Slits status ("shutter") output 4
23 Run / Stop output 5
5 Program number output (LSB) 6
24 Program number output (MSB) 6
6 Slits ("shutter") control input 7
25 Run / Stop input 8
7 Program number input (LSB) 9
26 Program number output (MSB) 9
8 Current position output (LSB) 10
27 Current position output 10
9 Current position output (MSB) 10
28 Ready output 2,11
10 Programmable timer output 1 12
29 Programmable timer output 2 12
11 Programmable timer input 1 12
30 Programmable timer input 2 12
12 Request position (LSB) 13
31 Request position 13
13 Request position (MSB) 13
32 Go to position input 14
14 New position output 15
33 Sync 16
15 Timed output (80196 HSO2) 17
34 Timed output (80196 HSO3) 17
16 Internal connection to pin 14  
35 Internal connection to pin 28  
17 Timed input (80196 HSI2) 18
36 Timed input (80196 HSI3) 18
18 +5 Volt power o/p  
37 Digital ground  
19 Analogue ground  


Notes

  1. The auxiliary DAC is normally used to carry the active wavelength, with 300nm giving zero, and increasing by 10mV per nm, i.e. 700nm gives 4.00V. However, alternative uses are possible in principle.
  2. The auxilliary ready input provides additional control over the system ready output. It allows the controller to delay the ready signal output (pin 28) until an external component is in place. If not connected, the auxiliary ready input floats high and has no effect, but if pulled low it will take the ready output low as well.
    Note: The system can also hold the ready output low for a precisely timed period, regardless of the status of the other ready control signals (see note 11).
  3. This pin is currently reserved for possible independent control of a shutter elsewhere in the system. However, the slits status output (pin 4) can already be used to control an external shutter synchronously with the shuttering action of the slits if required.
  4. Logic high when slits are open.
  5. Logic high when any of the system's four programs or scans is running.
  6. Indicates the currently running program number
  7. Logic high to open slits when Optoscan set to external slit control.
  8. Logic high starts currently selected program or scan. 4. Alternatively the go input (pin 32) can be used instead. These two inputs are ORed together by the internal software, to allow either or both of two external sources to control this function. If only one of these inputs is used, the other can be left disconnected, as all inputs are tied to ground via internal resistors. See also note 14 below regarding the shared functions of these pins.
  9. Up to four programs can be defined on the system. The program number to be run can be set using these inputs.
  10. Indicates which of the eight wavelength positions in the current program is selected.
  11. The ready output is high only when the grating and both slits are at rest in their correct positions. There is additional control over this output using the auxilliary ready input (pin 3, see note 2)
  12. The programmable timers and control gates are two sections of an 8253 timer chip. They are both clocked by the output of the third section of this chip, which is driven at 8MHz by the microprocessor clock. This facility is not currently supported.
  13. The system can be programmed to step between up to eight different wavelengths in each program. The current wavelength is encoded on these three bits (wavelengths 1-8 as numbers 0-7).
  14. The go input is active only when external position control is selected. The wavelength specified by the program number and position inputs (See notes 9& 13) is selected on the rising edge of the go input. Alternatively, the run/stop input can also be used, but for time-critical applications the go input is preferred. The length of the "go" pulse is not critical, although a value between 1usec and 1msec is suggested.
  15. A logic high pulse occurs whenever the system starts to change wavelength in any mode. The length of this pulse is at least 100msec. If dead time extension is in operation, it may be extended to a specified value of up to 50msec. Integration of signals by our photometry modules is disabled for (at least) the duration of this pulse.
  16. A logic high occurs here each time position 1 is selected during a program.
  17. Not currently supported

 

  1. The four HSO outputs from the 80196 give precision timed signals which we use to control the wavelength selection. Brief pulses on HSO0 set the times that the monochromator spends at each wavelength. The duration of each pulse is normally 10 usec, but it can be extended to keep the ready output low for the duration of the pulse, even if all the ready inputs are high. HSO1 is high for the duration of the first wavelength only, which is useful for synchronisation. HSO2 and HSO3 are potentially available for other uses.
  2. The four HSI inputs are not currently used by us, although HSI0 and HSI1 could be in the future. As well as serving as additional TTL-level inputs, the 80196 can record the times at which transitions occur on them with microsecond precision, and it can also use them as inputs to a 10-bit ADC.


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