Hi Peter,

On a slightly different topic, if you are not a member of the Lesvedome Yahoo group I urge you to join. It has a lot of very useful information about the Lesvedome system. The link below gets you there.

https://groups.yahoo.com/neo/groups/lesvedome/conversations/messages

There is currently running a very useful discussion on Bourne rotary encoders, see the topic called Gray Code Mode. One of the members, Steve Hennerly, has posted a link to some software he has written that works in conjunction with the Lesvedome User Interface software and measures the actual performance of the rotary encoder in real time. This will be very helpful for your testing. The output screen looks like this.

HTH

Regards, Hugh

Hi Peter,

One thing to bear in mind with your testing is that when the Lesvedome software is operating as designed, it will always stop the motor by making Relay 4 inactive before sending a signal to change motor direction via DO2 . After the change direction signal the software then starts the motor again. I think from memory that there is a delay of 75 milliseconds between the commands. Obviously you can't reproduce this timing manually when using the K8055 Demo software but I just wonder if you will get better results using the K8055 Demo software by always stopping the motor before you change its direction and then restarting.  Worth a go trying it this way anyway.

I can't think of any obvious reason why Relay 4 should latch on. Doing the tests suggested by Alan will be useful in finding the cause.

As for the motor stalling, I think you do need to change back to the earlier version of the Lesvedome software. Although the stall feature is useful I think it is probably too sensitive and will only complicate your testing. When everything else is working will be the time to see what happens when you run the latest version.

HTH

Regards, Hugh

Hi Peter,

Phew!! Well done! And a really good catch from Alan to spot that the DO2 / DI1 connection needed a blocking diode.

I am more than willing to try and help with the Lesvedome software but I should say that my set-up is far from typical in that I don't use relays I use the output signals from the VM110 board to drive a homebrew microprocessor set-up that lets me use stepper motors for the dome and shutter operation. I also use a 64 ppr Bourne encoder to measure my dome position. This gives too many pulses for the Lesvedome software to cope with so I use software to generate a reduced pulse rate that is fed back to the VM110. The other thing worth saying is that the Lesvedome forum and Pierre de Ponthiere, the Lesvedome software author are very helpful. It is also good to read the Lesvedome help files a few times as there is a lot of good information there.

For the Lesvedome software to operate with the VM110 board, as far as I know the only external things needed are these:

relays output signals on DO1 and DO2

position encoder input signals on DI1 and DI5

motor direction signal on DI4

home position switch signal on DI2 - Actually I am not sure this is needed  for testing with the Lesvedome User Interface as its only action  is  to reset  the dome azimuth position to the value defined in the Setup window.

As the relays are now operating as expected, the most likely cause of any remaining problems are from the encoder. On the Setup page of the LesvedomeNet User Interface try setting the Configuration Azimuth Sensor Mode to 'Hole to Hole' and also try varying the Timer interval. I believe the default value is 60 mS, you could try say 20 and 40 mS to see if that helps.

Let us know how you get on.

Regards, Hugh

Hi Peter,

There are dozens of similar models from Omron and I am probably wrong about using the 3009 model. I 'think' the one I used has 4 wires because it allowed me to switch between dark operated and light operated. The 3-wire dark on type (EE-SX3009) is perfect for what you want. When you look at the little internal circuit schematic on the data sheet it shows that the output is an 'open-collector' type so it does need a pull-up resistor connected to the +5 volt supply. The VM110 board has a 20k pull-up built in (2 x 10k resistors in series) on each of the digital inputs. This might be a bit high but try the sensor wired directly without an external pull-up first. If it doesn't work try adding a 1k external pull-up between the V and O connections.

HTH,

Regards, Hugh

Hi Peter,

Yep - there is a pic. I forgot that I actually mounted the sensor on a piece of aluminium angle and the aluminium was screwed to the wood block glued to the observatory wall.

IMG_2263.JPG

Hi Peter,

Have a look at the attached datasheet for the EE_SX3009. The gap between the two 'arms' is 5 mm wide and 10.5 mm deep. In my setup I use a length of brass strip about 3 mm wide and 1.5 mm thick. I mounted the brass on the flange of the dome so it sticks out horizontally and I mounted the sensor on a piece of wood glued to the side of the observatory. The brass strip is held to the flange by a single nut & bolt, not done up too tightly, so that if for any reason the brass bar hits the sensor, it will just bend out of the way.

I think there is a photo showing this in my SGL  photo album.

Regards, Hugh

en-ee_sx3009_p1_4009_p1.pdf

Hi Peter,

+1 for Alan's comments. I'm sure your UBEC would be fine.

Regards, Hugh

Hi Peter,

I'm a bit late to the party - again! Can you tell me which optical switch you have ordered? To confirm what Alan said, you really want an 'on when dark' switch and ideally one that will work with a 12 volt supply. The 3009 will work very happily with a 5 volt supply, as far as I remember, it's the one I use. 

Getting a +5 volt supply from the VM110 is possible and I'm sure the way Alan described will work but don't forget that the VM110 is getting all it's power from the USB connection to the Pi. So the Pi usb supply will be powering the Pi itself, the VM110 board, the encoder and the optical switch. I know it's late in the day but a 12 volt to 5 volt buck converter module with screw terminals only costs a pound or two and it would eliminate any possible power problems. Just a thought!

Good luck with tonight's testing.

HTH

Regards, Hugh

Hi Peter,

Thanks for filling in the chart. I have had a look and as far as I can see, Relays 1 and 2 are not operating. Relay 4 is operating as expected. I can't see any obvious reason why they aren't working but assuming your wiring is as per your Version 18 layout, then something is wrong.

The next test is to disconnect the wire that goes from DO2 on the VM110 to IN1- and IN2- on the relay board. Disconnect it at the VM110 end and then power up everything. Now touch the free end of the wire to ground (DC- connection on the relay board). Relays 1 and 2 should operate. If they do work then there is either a wiring fault in the connection to the VM110 DO2 terminal or a problem with the VM110 board. Obviously check the wiring very carefully

If they don't work you need to check that your voltmeter shows about +12 volts at the IN1+ and IN2+ terminals. If that voltage isn't right, I would suspect a wiring fault in the links between the 5k resistors.

If there is about +12 volts on the IN1+ and IN2+ terminals, try a new, direct wire connection from IN1- to the DC- connector. This should cause Relay 1 to operate. Repeat with IN2- to DC- and check if Relay 2 operates. 

If the relays still don't work with a direct connection to ground on INx1- and +12 volts on INx+ then I think the relay board may be  faulty.

HTH

Regards, Hugh

Hi Peter,

I am confident that the 2.79 volts from the encoder is enough to drive the Digital Inputs on the Velleman board, so I don't think you need worry about that and you haven't fried the encoder. 

I think that the reason you found the VM110 as Device 3 is that you haven't installed the two jumpers (little shorting links) . This won't have any bad effects but you will need to tell the Lesvedome software that the board is at address 3. The text below is from the Lesvedome help file.

In Dome and Switch Setup windows, select the address of your Velleman board (0 to 3) in accordance with the  jumpers SK5 and SK6

SK5 installed     and  SK6 installed         address = 0
SK5 unstalled    and  SK6 installed         address = 1
SK5 installed     and  SK6 unstalled        address = 2
SK5 unstalled    and  SK6 unstalled        address = 3

For your debugging I think the easiest way to do it is by checking only one thing at a time. If it was me, I think my approach would be like this:

Remove ALL connections from the VM110 board. (But remember where they all go)

Connect the VM110 directly to my computer via a USB cable.

Run the Velleman demo software and, using your voltmeter, check the board is working. I would be very surprised if it's not but if it isn't then I think the only option would be a new board - sorry!

OK - the board is working fine. Next we need to get the relays working. What will help here is to connect the relay board to the VM110 but do not connect the encoder or the Hall switch. In other word only connect the DO1 and DO2 terminals on the VM110. Nothing else!

Now see what happens when you use the demo software to switch outputs 1 and 2 on and off. You can use your voltmeter to measure the voltages at the relay board COM1 and COM2 terminals. From your post on Friday, it sounds as if DO 1/Relay 4 is working as planned but there are problems with DO2/Relays 1 and 2. I suggest that you make a table in Excel that shows the voltages on all the relay output connections for each value of DO1 and DO2

With luck, this should be enough to spot any problems with the relay board or the wiring. Post a copy of the table if you are stuck, we can all have a go at deciphering what's going on.

When you have got the relays working as they should, I think the next step is to connect the rotary encoder to the VM110 and check that you see the ticks being counted using the demo software. Then the Hall switch, again using the demo software to make sure it operates as you expect.

Only at this point would I think about trying everything using the Lesvedome user interface software - not he full blown ASCOM driver, just the user interface and still using a direct USB connection to your computer.

OK - so far so good? Now add the Pi to the mix and see if it all still works? It does - congratulations, you have an automatic observatory!

HTH

Regards, Hugh

Hi Peter,

I am afraid that due to family problems I won't be around much today. I will be back again later on this evening and if you are not sorted by then will offer any help I am able to.

Regards, Hugh

Peter,

I am fairly sure that Lesvedome does need the encoder output to work. You can test the operation of the encoder on the bench using the Velleman board software. Goto https://www.velleman.eu/support/downloads/?code=VM110 and download the 'Complete SDK Pack for K8055 / VM10 (Rev 4.0). Download and unzip. You will find a little program called K8055N_Demo.exe.

I suggest you start with a direct USB connection to a Windows PC without using the Pi as a relay. When you run the software and turn the encoder shaft (with the encoder powered of course) you should see the count increase in one of the windows. 

If you don't see this you will need to investigate further. But - hopefully - you will get a positive confirmation that the encoder is working and sending a signal to the Velleman board.

HTH

Regards, Hugh

Hi Peter,

It sounds as if you are nearly there! The main thing I would recommend at this stage is don't try and connect everything at once. Just connect the Pi and use the Lesvedome User Interface to see if you can get the correct relays to operate. There was a recent change to Lesvedome - I quote

Hello Nicolàs

Good Luck!!

The Lesvedome User Interface is a nice, simple way of testing if the hardware works - or not!

If you haven't already downloaded this it's automatically downloaded when you download the Lesvedome ASCOM driver. The User Interface is a stand alone program that is used to input the configuration parameters for the dome and azimuth sensor and to test the operation. After the original download you can find the UI program in C:\ProgramFiles (x86)\Common Files\ ASCOM\Dome\ASCOM.LesveDomeNet\ASCOM.LesveDomeNet.exe. I suggest you create a shortcut to the program as it is rather tucked away.

HTH

Regards, Hugh

Hi Peter,

Have a look at this table. https://www.engineeringtoolbox.com/wire-gauges-d_419.html

For single core cable, 18 awg would be OK but 16 awg would be a bit safer. If the cost difference isn't too much I would recommend 16 awg wiring.

Regards, Hugh

Hi Peter,

Another couple of comments about your circuit. First, you are showing a connection between DI3 and DO3. This is not needed for your application. Or - more accurately - it is only needed if you are going to use the Lesvedome ASCOM Switch driver. For the ordinary ASCOM rotation driver, it isn't needed. It won't do any harm and feel free to leave it in but I thought I would clarify a bit.

The second comment might be more important. You show a diode in the connection between DO2 (dome motor direction signal) and DI4 (tells the Lesvedome software what the dome motor direction actually is).  This connection is definitely needed for the circuit to work but the diode is not required. My setup works perfectly with just a piece of wire connection the two. If you look at the Charles Harrow schematic, which is considered the 'gold standard' for implementing the Lesvedome system, there is just such a direct connection. As we have discussed, the Velleman digital outputs are ACTIVE LOW, so the diode orientation is correct but it introduces a voltage drop of 0.5 - 1.0 volts and this MIGHT be enough to cause problems. Better to leave it out and just use a piece of wire. And think of all the money saved!!!

HTH.

Regards, Hugh

Harrow_Schematic.pdf

13 minutes ago, pmlogg said:

Alan

Re-reading your post, should I still have a link from DC- on the relay board to one of the GRD connections on the VM110?

Thanks

Peter

Yes!

Regards, Hugh

Hi Alan,

With the extra ground connection from NC1 / NO2, it looks like everything is good.

Regards, Hugh

Hi Peter,

One problem with your latest layout drawing is that you don't have a connection between the ground of the 12 volt supply and the DC- connection on the relay board. You do show a connection between the Relay board DC- and the GND connection on the Velleman board but these boards are using separate power supplies and there is no common ground rail. 

Alan's drawing for this is correct - he shows all the modules connecting to the SAME ground point. You do need this connection and it needs to be one with a decent wire size as all the motor current will flow through it. 

I am struggling a bit with Alan's drawing of the relay switching as I can't see a path for the current through the motor to ground - this may well just be me but as I see it when Relay 4 operates - to turn on the motor - it connects NO4 to the 12 volt rail. This then connects 12 volts to NC2  and NO1.

Relays 1 and 2 are the motor direction relays and are both switched by the Velleman DO2 output. As drawn, with the relays in the NC position, NC2 sends 12 volts to one side of the motor. The other side now needs to be connected to ground. However, it is connected to COM1 and NC1 - as Relay 1 is not activated - and also connected to NO2. At this point the path ends - no connection to ground, no motor turning...............

Final point - sorry to be so negative. You DO NOT NEED a resistor in the supply line to the Bourns encoder!!!!!!!! I think I know who recommended this and it is just plain wrong. I have attached the manufacturer's data sheet for the EM14 range. All that is needed is a connection to a 5 +/- 0.25 volt supply.

I will have a look at the relay circuit in more detail later - as I said I could be wrong on this but at the moment I can't see it working. 

HTH,

Regards, Hugh

BournsEncoder.pdf

Peter,

I'm sure you know this, but in order for the relay to operate, as well as connecting the IN+  and IN- terminals,  you also need to have the relay board connected to the 12 volt supply. The relay won't operate if you are only connecting to the IN terminals.

Regards, Hugh

Alan,

Good analysis! I think you are spot on and the voltage measurements show that there is a current limiting resistor in series with the photodiode. Hopefully, Peter's tests will confirm that the relay will operate as required with the IN+ terminal connected directly to the positive rail when the IN- terminal is shorted to ground. It's a nice idea of yours to order a relay board yourself. They do seem useful things to have around.

Regards, Hugh

Hi Peter,

I think one resistor will be fine - perhaps Alan could confirm that?

Do you have a multimeter with an ohms range? If you do, you can check to see if there is a suitable resistor already fitted on the relay board. With the board not connected to anything else, measure the resistance between IN1+ and IN1- with the red multimeter lead connected to IN1+. Then swap the meter leads over and measure again. If one reading is a few thousand ohms and the other very high then there is a suitable resistor on the relay board and you don't need an external one. Just connect all the IN+ terminals to your 12 volt supply.

If you don't have a multimeter I do recommend you get one - it will be really useful when you build your dome driver. This one from Amazon looks OK  and not too expensive.

https://www.amazon.co.uk/Pocket-Digital-Multimeter-Ranging-Multimeters/dp/B015Z451ZY/ref=sr_1_9?crid=2TO2WULPN4THF&keywords=multimeter+tester&qid=1558353050&s=gateway&sprefix=multimeter%2Caps%2C188&sr=8-9

HTH,

Regards, Hugh

1 hour ago, newbie alert said:

Was this all within your spacing to sensor distance? Have you still got a flat field with the stars looking good at edge of the field?

Yes to flat field and stars looking good to the edges - but this was with my Tak 106 so no issues with getting an exact spacing distance.

Petzval rule OK!

Regards, Hugh

Hi,

The setup I use for an OTA mounted computer / controller comes in around the £700 mark, so a lot cheaper than the Eagle. My equipment is a  Kodlix GN41 fanless mini-computer. with a Pegasus Ultimate power box. The Kodlix runs on 12-15 volt power and comes with Windows 10 Pro pre-installed. I added an internal SanDisk Ultra 500 GB SSD which is overkill really. The Kodlix runs all my imaging software without any problems. Works a treat!

HTH,

Regards, Hugh

Hi Aidan,

With my ZWO 8-pos wheel, I used homemade spacers cut from aluminium cooking foil. This is very thin and I used a stack of 4 or 5 - can't remember exactly. By using a stack I was also able to get pretty much all square. I made the spacers by making up a stack of squares first, then used ordinary scissors to cut out the rings. Tedious and took a couple of tries but it worked eventually.

HTH

Regards, Hugh