TB6600 and HBS57H differential mode?

Dear Forum,

I read the manuals of both types of my driver but I am still unclear whether they support differentail mode. I have seen a couple of connection diagrams and they show DM542 inputs connected to step+ and step- on the mesa card rathern than step+ and ground or step- and 5V as described in the manuals.

How can I find out whether these drivers support differential mode? Am I right that a driver offering both common cathode as well as common anode mode has to be capable to be used in differential mode? To my understanding this is only possible if neither the cathodes nor the anodes are connected. Correct? Thanks in advance,

Louis

Connect them to the step+ and step- and leave out the 5V and GND.
Same for dir. Leave the enable unconnected, unless you actually want to control it.

Thanks! So, you are basically saying, yes they support differential mode, right?

Is there a good reason not to use the enable?

The differential mode only makes sense if there is a differential receiver at the driver input. When the driver input is optron, connecting to the differential output of the card does not produce any effect, just the additional load of the second output pin, which works here instead of + 5V or GND.

I'm not sure we're talking about the same thing. Differential connection from card (for example some Mesa) and driver is usually realized according to RS422 standard.
On the side of the card the output levels are in the range of 0-5V, both signals have always the opposite level. So the difference between them is maximum 5V, in practice less.
If the differential transmission is to be of any benefit, on the driver side there should be a differential receiver which evaluates the difference between these two signals.
If there is only an optron on the driver side, its LED lights in one polarity of difference, in the other it is in the reverse direction. Thus, differential transmission has no positive benefit here. On the contrary, in the reverse direction, the optron is stressed by the reverse voltage, which for most optrons is at most about 5V.

I don't think it is actually differential in the meaning that one signal level is +5V and the other -5V.
It is more that there is a floating ground I would say. Signals are between 0 and 5V, but "0"
isn't necessarily the same potential as ground. I would say that is what an optocoupler expects
but it shouldn't hurt to feed it -5V.

this drivers like to get set by 5V and act on GND
as most parport support 5V to the Step DIR ENA
so it is Noicefree as the controller needs realy to pull the GND

i recomend to get the 5V to the + Signals

getting the enable pin is also a good idee
if you do it on pin14 and dont need this extra pin
WHY no powerup on mashine power
you can get a low level Mashine enable
so you can tweek if you need Steppers can be driven slightly higher RMS
as they will be shut down by the control
the internal HALF Amps is also a better trigger and a softer start

there are multible reasons for getting enable to work
most controls got them all 6Axis to one enable pin


IF you can go for a real good driver use the DM556 this are realy the best you can get on low cost hobby cnc

Hakan wrote:

I don't think it is actually differential in the meaning that one signal level is +5V and the other -5V.
It is more that there is a floating ground I would say. Signals are between 0 and 5V, but "0"
isn't necessarily the same potential as ground. I would say that is what an optocoupler expects
but it shouldn't hurt to feed it -5V.

Differential signals in the CNC are mostly in the range of 0 .. + 5V (not -5V .. + 5V). So the difference between the signals is maximum 5V (in practice usually up to 4V).
The transmitter can consist of two TTL or CMOS outputs, where the two outputs are inverted to each other.
The differential receiver cannot be realized so easily, since the receiver has to evaluate the difference between the two signals, even if these signals are shifted from GND up to several volts.

Thanks for all the great input. For other readers and to be sure I got all points the results of this discussion are:

Does the TB6600/ DM542A support differential mode?:

• No, a differential receiver is pretty expensive to build. Having seperated grounds has nothing to do with differential mode
• They use standard optocouplers without a shared ground enabling two directional input

How to correctly connect the TB6600/ DM542A?:

• The correct mode is to connect either 5V constant and pulse- /dir- /enable- or use a common ground and pulse+...
• Connecting pulse+/pulse- e.g. is possible but not really advantageuos since it might run optocouplers out of spec, raise energy consumption (and by this noise emission)

Correct?