Berthoud/Trimble speed signal

[cosmagedon]

I'm trying to get a speed signal to my Berthoud sprayer control box, I usually use it on a tractor with a 7pin iso plug as it came wired up this way. Now I want to use it on a Tm155 so I haven't got the ìso plug option.

The Tm goes on the fert spreader and a Trimble Ez250 gives the spreader a speed signal to vari the rate so I know this works ok. I've made a new adapter loom so I can plug the berthoud control into the Trimble loom but I can't get the berthoud to register any speed.

I've double checked all the pin outs are ok, I've adjusted the pulse input up and down in case it was going out of range and it still just sits at 0 not even flickering.

I also use the fert spreader on the other tractors with another loom plugging into the 7pin iso plug so I know they both use the same signals ok.

Has anyone got any ideas as to what I'm missing?

 

[PSQ]

Whats the control box on the Berthoud?

IIRC, the Trimble 500's could either output speed or a 'simulated radar' signal, I'm guessing you'll need to select the correct format in the Berthoud box. I wouldn't change the Trimble settings, as it will mean you need to keep changing it back for the spreader.

 

[Pheasant Surprise]

I'm trying to get a speed signal to my Berthoud sprayer control box, I usually use it on a tractor with a 7pin iso plug as it came wired up this way. Now I want to use it on a Tm155 so I haven't got the ìso plug option.

The Tm goes on the fert spreader and a Trimble Ez250 gives the spreader a speed signal to vari the rate so I know this works ok. I've made a new adapter loom so I can plug the berthoud control into the Trimble loom but I can't get the berthoud to register any speed.

I've double checked all the pin outs are ok, I've adjusted the pulse input up and down in case it was going out of range and it still just sits at 0 not even flickering.

I also use the fert spreader on the other tractors with another loom plugging into the 7pin iso plug so I know they both use the same signals ok.

Has anyone got any ideas as to what I'm missing?

Check this...you need to amplify the pulse output voltage using the pull up resistor method that Sleepy did. otherwise the pulse voltage is too low to be detected by the input on the Berthoud box...

https://thefarmingforum.co.uk/index.php?threads/kverneland-focus-2.168994/#post-3740654

 

[cosmagedon]

Whats the control box on the Berthoud?

IIRC, the Trimble 500's could either output speed or a 'simulated radar' signal, I'm guessing you'll need to select the correct format in the Berthoud box. I wouldn't change the Trimble settings, as it will mean you need to keep changing it back for the spreader.

I think the 250 is the same in that case, I've got radar switched on and pulses/km set on the Berthoud, it's a DP Tronic control box.

 

[cosmagedon]

Check this...you need to amplify the pulse output voltage using the pull up resistor method that Sleepy did. otherwise the pulse voltage is too low to be detected by the input on the Berthoud box...

https://thefarmingforum.co.uk/index.php?threads/kverneland-focus-2.168994/#post-3740654

That sounds just what I'm looking for! It would make sense why the fert spreader works ok but not the sprayer. I will grab a 10k resistor in the morning and have a play, do you think a diode would be a good idea so I don't send any voltage back to the Trimble, or is it only current draw that's an issue?

 

[Pheasant Surprise]

That sounds just what I'm looking for! It would make sense why the fert spreader works ok but not the sprayer. I will grab a 10k resistor in the morning and have a play, do you think a diode would be a good idea so I don't send any voltage back to the Trimble, or is it only current draw that's an issue?

A “genuine” radar output will be switching between 0 and 12 volts on the output speed pulses. It would apppear that the EZ250 only switches it’s simulated radar output between 0v and 3v ~ 5v or thereabouts. So on some boxes that lower threshold voltage may work....and on others it will be too low to reliably trigger the input.

The pull up resistor works by tieing the radar input pin to 12v, then when the 250 pulls its radar output pulse low, it pulls that input pin down to 0v so you get the “full” 12v for the pulse change - so it triggers correctly. The pull up resistor stops too much current getting drawn/sunk from these I/O supply pins including the EZ250.

I’d say the EZ250 probably has got clamping diodes built into the I/O of the unit. An extra external diode in series will reduce the little output voltage from the pin, so any benefit may actually be a hindrance.

 

[cosmagedon]

A “genuine” radar output will be switching between 0 and 12 volts on the output speed pulses. It would apppear that the EZ250 only switches it’s simulated radar output between 0v and 3v ~ 5v or thereabouts. So on some boxes that lower threshold voltage may work....and on others it will be too low to reliably trigger the input.

The pull up resistor works by tieing the radar input pin to 12v, then when the 250 pulls its radar output pulse low, it pulls that input pin down to 0v so you get the “full” 12v for the pulse change - so it triggers correctly. The pull up resistor stops too much current getting drawn/sunk from these I/O supply pins including the EZ250.

I’d say the EZ250 probably has got clamping diodes built into the I/O of the unit. An extra external diode in series will reduce the little output voltage from the pin, so any benefit may actually be a hindrance.

Tried a 10k resistor today as a pull up and it still wouldn't work, I wired it first to the back of the amphenol plug and it didn't work but the berthoud box only gives out 8v so I though it might still be too low. Next I tried it with a proper 12v output from the Trimble and it still won't work! I haven't got a oscilloscope to see exactly what's happening but with my multimeter I'm getting just under 7v when moving.

Any other ideas?

 

[PSQ]

Any other ideas?

If the Berthoud box isn't detecting either the Trimble speed or simulated radar output, then call Berthoud and see if they have a solution.
It may not involve the Trimble unit, or it may require a different one (I have a 500 for sale, but I dont have a spare Ag15 antenna to go with it), or perhaps Berthoud have a radar kit to suit?

Or, (I dont know the Berthoud range) is there a way to feed in an NMEA signal ('serial control') to the box?!

Or as a last resort it's back to using a wheel sensor on (an un-driven) wheel.

 

[Pheasant Surprise]

Tried a 10k resistor today as a pull up and it still wouldn't work, I wired it first to the back of the amphenol plug and it didn't work but the berthoud box only gives out 8v so I though it might still be too low. Next I tried it with a proper 12v output from the Trimble and it still won't work! I haven't got a oscilloscope to see exactly what's happening but with my multimeter I'm getting just under 7v when moving.

Any other ideas?

Have you checked the simulated radar frequency output on the Trimble setup matches what the Berthoud is expecting to see (I think the Berthoud box expects 16 pulses per wheel rev, but I could be totally wrong....something I saw somewhere)?

Has your multimeter got a frequency count function? If so can you check the frequency output from the Trimble radar speed pin 9 at a set speed, like at 10 kph. Compare against the frequency reading from 7-pin signal socket on the other tractor at the same speed. If the DP Tronic box works from the 7-pin socket, then it’s a matter of making sure the signals are the same amplitude and expected frequency.

If frequency output is good, then if needed another way of amplifying the switching pulse output would be to use a couple of cheap NPN transistors and some resistors to create a small signal amplifier.

 

[cosmagedon]

If the Berthoud box isn't detecting either the Trimble speed or simulated radar output, then call Berthoud and see if they have a solution.
It may not involve the Trimble unit, or it may require a different one (I have a 500 for sale, but I dont have a spare Ag15 antenna to go with it), or perhaps Berthoud have a radar kit to suit?

Or, (I dont know the Berthoud range) is there a way to feed in an NMEA signal ('serial control') to the box?!

Or as a last resort it's back to using a wheel sensor on (an un-driven) wheel.

I dont think the berthoud box will take a nmea input, it's only a radar signal. I will try and give John Rhodes a ring tomorrow and see if anyone can point me in the right direction, I could run a sensor on the wheel like you say but I would prefer to use the trimble so I can swap it from machines easier if I need to.

I'm also waiting for a oscilloscope off a friend one night this week so I can see what the trimble is actually pumping out.

 

[cosmagedon]

Have you checked the simulated radar frequency output on the Trimble setup matches what the Berthoud is expecting to see (I think the Berthoud box expects 16 pulses per wheel rev, but I could be totally wrong....something I saw somewhere)?

Has your multimeter got a frequency count function? If so can you check the frequency output from the Trimble radar speed pin 9 at a set speed, like at 10 kph. Compare against the frequency reading from 7-pin signal socket on the other tractor at the same speed. If the DP Tronic box works from the 7-pin socket, then it’s a matter of making sure the signals are the same amplitude and expected frequency.

If frequency output is good, then if needed another way of amplifying the switching pulse output would be to use a couple of cheap NPN transistors and some resistors to create a small signal amplifier.

On the Berthoud box you can first set the wheel circumference and pulses. If you leave this on zero you go onto pulses per km.

Once I get a scope I will have a look on both and see exactly what I'm getting.

 

[Pheasant Surprise]

On the Berthoud box you can first set the wheel circumference and pulses. If you leave this on zero you go onto pulses per km.

Once I get a scope I will have a look on both and see exactly what I'm getting.

A scope is good if you can get your hands on one, to see what’s what. Shouldn’t be too hard to get things matched up. Good luck with it all.

 

[KennyO]

@cosmagedon I was told that you can get a speed signal out of a TM by my local service manager. Was going to do it on ours for fert spreader back up but never did. From memory he told me that there was wiring for it under the RH panels. Take out the EMU panel and see if you can find anything.

 

[cosmagedon]

@cosmagedon I was told that you can get a speed signal out of a TM by my local service manager. Was going to do it on ours for fert spreader back up but never did. From memory he told me that there was wiring for it under the RH panels. Take out the EMU panel and see if you can find anything.

That's handy to know, I hadn't heard that before but I will have a look at the drawings when I get a chance.

Update, I spoke with a helpful guy called James at John Rhodes and he said I might need to swap the wiring around inside. Turns out someone had already been in and swapped the wires about and was using the Vpnp pin with the iso plug, I swapped a spare wire around into the Vnpn pin and changed my loom to match, bingo now works ok!

 

[Pheasant Surprise]

Turns out someone had already been in and swapped the wires about and was using the Vpnp pin with the iso plug, I swapped a spare wire around into the Vnpn pin and changed my loom to match, bingo now works ok!

That makes sense now (with 20/20 hindsight!) - just looked up the D.P.Tronic wiring diagram. Can clearly see the two inputs on pins 17 and 18 for use with either NPN or PNP type 3-wire proximity sensors.

If not using such a sensor (as you are), then you would need to swap to the correct input, depending on whether the radar output is behaving as "switched positive" or "switched negative". Speed signal output from tractor's 7-pin ISO socket will behave like a PNP and simulated radar from Trimble must behave like NPN.