Messages

361

General Mach Discussion / Re: Brain Refresh Rate

« on: July 17, 2009, 07:12:14 AM »

Well there you go, I learned something else today.

362

General Mach Discussion / Re: Brain Refresh Rate

« on: July 17, 2009, 02:10:42 AM »

10Hz I seem to recall.
Hood

10Hz is for the Macropump.

As far as I understand, the Brains run at KHzs or 10s of KHz, possibly even faster.

That was the big improvement over the macropump.

Cheers,

Peter.

363

General Mach Discussion / Re: Limit switches on modbus/TCPIP

« on: July 16, 2009, 05:57:28 PM »

Well that is a downer. I did notice there was some latency when reading the switches. I have been able to get the second parallel port working with Mach3 so the Adam-6051 is more of a toy anyway.
That leads me to another question, why 25ms?

25mS is the resolution that you can ask Mach3 to poll the modbus devices, so worst case is that the limit switch closes just after Mach3 has polled the device and the limt switch closure won't be detected until the next read.

Cheers,


Peter.

364

General Mach Discussion / Re: Limit switches on modbus/TCPIP

« on: July 16, 2009, 12:24:46 PM »

You can't use any form of modbus for hi speed I/O like homes/limits. The latency between the switch actuation and Mach seeing it will be too great causing all sorts of variance in the sensed position. Modbus I/O is good for thin.gs like user interface switches and lights, or a program running on a PLC that Mach only needs to know the status of

Yes Jeff is correct. When reading Modbus at 25ms (40Hz) you can have a varing delay of up to 40mS, so it is no good for home switches.

You can use Modbus for limit switch depending on the dynamics of your machine and how far it moves in 25ms. That said a more responsive input such as through the parallel port or Smooth Stepper is desirable.

Cheers,

Peter.

365

General Mach Discussion / Re: Are We Losing CNC Vendors???

« on: July 02, 2009, 07:04:13 AM »

Hi Guys,

As far as CNC vendors go, I'm sure I'm at the smaller end. In fact I still need a day job as a Systems Engineer to pay the Mortgage.  Every now and again I get sent interstate for a day or two which causes distruptions to my Homann Designs business.

All of the boards I sell are designed and manufactured by myself. I don't get stuff made by cheap labour in other countries or take shortcuts. I design the circuits, do the pcb layouts, write the manuals, do the SMT assembly with a pick and place machine and do the through hole assembly with a soldering robot or by hand. Test the boards, pack the orders, and ship them.

Every now and then I get a bit behind, instead of an order being shipped out in a day or 2, it may take 5 or 6. That said, I do endevor to get things done as soon as possible.

One of the frustations is that I have a mind full of ideas that I want to investigate and implement, but struggle to find the time to do so. So in the end my new developments  occur too slowly, as does the documentation. In the end many of the ideas will stay just that, ideas.


Cheers,


Peter.

366

Modbus / Re: Mach modbus inteface info?

« on: June 28, 2009, 10:31:46 PM »

Hi Mark,

All is clear now. Your making the same mistake that the engineers at Huanyang  have.

Yes the spec says the modbus serial pdu contains

Address
Function Code
Data
CRC

BUT, you need to see what the definition of the Data field contains for each function code. For that you need to look at the document

http://www.modbus.org/docs/Modbus_Application_Protocol_V1_1b.pdf

For instance Function code 03 (Read holding registers) on page 15 shows the Data field contains 2 sub-fields as shown below.

Data.starting address        2 bytes  =  0x0000 - 0xFFFF
Data.quantity of Registers  2 bytes =  0x0000 - 0x7D


And, the Data field in the response to this contains;

Data.bute count       1 byte         =  2 x N
Data.register valuess  N x 2 bytes  = 0x0000 - 0xFFFF

where N is the quantity of registers.




Cheers,

Peter.

367

Modbus / Re: Mach modbus inteface info?

« on: June 28, 2009, 09:26:18 PM »

Hi Mark,

I just edited my last message.  I meant to say that if the message was as you described, then it is not Modbus compliant. You cannot change the format of the modbus messages that Mach3 sends.

Modbus requires you to provide the start address and the quantity of registers/coils being read.  You can't get around that in Mach3

For whatever reason, Huanyang  have not implemented the protocol correctly. It may have been a translation problem.

If you look at the Modbus config page for the Modbus I/F with Plugin support, you will see the required fields.

Let me know if that is not clear.

Cheers,

Peter.

368

Modbus / Re: Mach modbus inteface info?

« on: June 28, 2009, 08:07:57 PM »

Hi Mark,

If the message format is as below, then it does not meet the modbus spec. Mach3 uses a Modbus compliant library. There is no way to make it non standard.


1 byte slave address
1 byte function (which is workable with the Huanyang except 02 and 03 are seen as writes in it rather than reads)
N x bytes data
2 bytes CRC

I'm thinking of making a small converter board that takes in Modbus on one side and outputs the Huanyang  protocol on the other.

Cheers,

Peter.

369

General Mach Discussion / Engineering Note for a 4 Axis G251 Controller

« on: June 23, 2009, 07:49:30 AM »

Hi,

I just finished a new Engineering note EN009 that shows a System Schematic Of
a 4 Axis controller that uses the MB-02 BOB, DC-03 V3 DigiSpeed and four Gecko
G251 drives.

The Engineering note EN009 can be found at the bottom of the following page.

http://homanndesigns.com/store/index.php?main_page=product_info&products_id=59

Cheers,

Peter.

370

General Mach Discussion / Re: Aluminum for cutting PCB solder paste stencils

« on: June 19, 2009, 09:30:12 AM »

Hi Kevin,

Sorry, I get them made.

I have seen home made stencils that just drill holes rather than routing. Just use a drill bit that is the width of the pad. In rectangular pads drill 2 holes.

Cheers,

Peter.