Differential Signals On A and B Axis

[buschbwbusch]

I am using AC servos whos drives require a differential signal. Unless I am wrong it seems as though I cannot just jump the G from the B or A axis and use that as the - side of the pulse. Is there a way Masso can use there TTL outputs to come up with a solution for differential signals? Or is there another method of solving this problem.

 

[masso-support]

Yes you can join the two -ve signals of your motor drive together and connect to the G signal and the +ve signals to S+ and D+

 

[buschbwbusch]

Tried that it is a no go. I will check the wiring over once more. However if it is totally necessary to get P+/P-,D+D- can it be done

 

[masso-support]

Can you please provide your drive model and a link to the user manual.

 

[buschbwbusch]

Here it is

 

[buschbwbusch]

Pg 67 has some interesting info...not sure if it potentially impacts things or not

 

[masso-support]

Thanks and yes the wiring that we mentioned is fine and will work, the one thing now would be that the parameters need to be set for the drive to be able to see those signals, see page 73 and set the Position control parameters to Pulse + direction.

 

[buschbwbusch]

Checked that already as well if I am looking at the manual correctly...pn096=0 is p+direction. The thing is when I swap x y or z connectors the motor moves fine... so it would not appear to be a drive setting. The difference appears to either be the baxis itself or the signals. I will swap to a and get back to you tomorrow

 

[buschbwbusch]

Still nothing...Can u describe quick way to test if signals are coming out of a and b axis on Masso? If I jog the axis and check with volt meter set to dc should I be able to see +\_ voltage between p+ and g and also d+ and g as it is jogging? Or does it switch too fast to see and I need something more sensitive like o scope?

 

[masso-support]

1. What version of the MASSO software are you running.
   
2. When you jog the A or B axis do you see the A or B axis numbers change on the screen.
   

 

[buschbwbusch]

I am running the latest update sent out now.Yes the numbers are moving for both axis when jogged. So now I need a way to see if the signal is coming out of controler. Will the voltmeter work to do this? I am fuzzy on how the step direction actually works. Is it +\_ 5v or less like ttl where there is a threshold high vs low either way if I can find a way to at least see them change state then I can suss that part out

 

[masso-support]

Checked the drive manual again and it should work.

1. So you connected PP- and PD- to the G on the Axis connector?
   
2. PP+ to S+ on the Axis connector?
   
3. PD+ to D+ on the Axis connector?
   

 

[buschbwbusch]

OK I got it to work..sort of. It will only go in 1 direction though. I had the same kind of current flow issue with the VFD as well. The issue appears to be I cant have the same common for either the +or-.

So right now the G is jumped to 3 and 4
Pulse+ goes to pin 14 which is the - side according to the schematic as laid out in the manual
Direction+ goes to pin5 which is the - side as well

 

[masso-support]

So that means that in the motor drive manual they have the polarity marked wrong.

Now the motor is turning but in one direction only? With a multi-meter connect the -ve of the meter to G and +ve to D+ on A axis connector, when you chnage the direction of motion of A axis you will see the voltage change between 0 to about 5v.

 

[buschbwbusch]

OK I checked it out with Voltmeter. And it works as you described until I wire it to the drive. Then as the current flow is different from step to direction, when it is wired the way it will work with the P+ going to the - side of the pulse and the G going to the + side of the pulse it will only go in one direction. I have done enough figuring to know for sure that the only way this is going to work is if the D- and P- do not share a common. Is there a way to use one of the TTL outputs to take care of the direction? The step is not a problem, but them sharing a common is just not going to work. I know what the manual is showing, but I am now 100% sure it will not work the way it is.

 

[buschbwbusch]

In looking at the difference between how the XYand Z deal with the direction command it makes a little sense to me. On the XYZ axis if i check with voltmeter the direction is moving from a +3.5Vto-3.5V and to 0 with nothing moving. On A and B I get 0 or +5 between g and D+. Again the pulse is working now it is just only moving in one direction. On Page 67 of manual there is some information about how to change what the direction signaling is looking for, can you shed some light on that. Or best possible solution can a TTL output be used to fix this problem with a little logic on your part? I am so close to getting this thing all working, and this is throwing up a rather large road block.

 

[masso-support]

I am unable to understand why the drive is doing this, the biggest problem is that you cant even believe these Chinese drives or manuals.

1. As per the manual (below image from page: 22) it should work. The differential signals have voltage below 5v and yet they work with the drive but the 5v signal from A axis will not work, just does not make sense.
   
2. Can you connect the drive to A axis as told earlier and measure the voltage on the D+ and G signals while the drive if powered and connected to MASSO.
   

 

[buschbwbusch]

I agree it does not make sense. I have tried the A and B axis both and its the same result. The only way I can actually get any movement of any kind is to wire g to pin 3 and pin 5 and then P+ to pin 14 and D+ to pin 4. Then it will only move in one direction. If I measure the voltage between the D+ and G as described when running. I get 1 +5V to a +.23V it never goes back to zero when letting off jogging it just kinda toggles in that direction and stays until the direction is reversed and then stays going that direction.

 

[masso-support]

.23V is ok and it does not have to be exact 0.00.

Not sure if you have tried this earlier, can you only swap the PD+ & PD- wires from drive to MASSO and give it a try, please also measure the voltage at the same point and let us know.

 

[buschbwbusch]

Does same thing one direction only. Ok let s start brainstorming solutions. I know a +3.5 to -3.5 v will change direction and I am getting 5v out of theD+ so how can I get 3.5 v-and the Masso to switch it beween the two.

1. Get ssr and use 5v to switch from between + and -. Since it should only move when it gets a pulse I should be good, can I get the -3.5 volts out of a Ttl output?