[poldim]

So I've been given some old demo cases from a sales rep for Schneider Electric. Among them are 6 BSH servo motors and 5 Lexium 05 Drives and 1 Lexium 15 Drive and an Altivar 31 VFD. I'd like to design a CNC build around this hardware but wanted to get some background on the electronics of it.

Per the user manual, the LXM05 drives accept analogue, pulse direction and fieldbus (CANopen and Modbus) interfaces for control. What is the best way of establishing the communication between the software (Mach3) and the hardware (LXM05)? Is this the easiest? Most robust?

Lexium 05 User Manual HERE

[Al_The_Man]

Analogue drives and Mach can be Dynomotion/Kanalog or EMC (not Mach).
Al.

[poldim]

Analogue drives and Mach can be Dynomotion/Kanalog or EMC (not Mach).
Al.

I'd only want to use analog if that's the only alternative. I have seen based on several online sources, that mach3 supports modbus. Does anyone have experience with using it? How much custom programming is required for this?





http://www.homanndesigns.com/pdfs/Us...with_Mach3.pdf
Document outlining Mach3 with Modbus.


The video below shows mach3 communicating with a PLC, but for my setup this is overkill. I'd only need mach3 on a PC communicating directly to the servo drivers.
Modbus Communication Test between PLC and Mach3 CNC Software - YouTube


Making Modbus device communicate with a PC
Per the thread above, I would only need a serial port on the PC (other than possibly some gender benders) to communicate over RS232. If RS485 is needed, something like RS-232 to 422/485 Serial Port Converter - B&B Electronics could be used. Realistically, I would have to use a USB to serial adapter since most machines do not have serial ports anymore. Hopefully this wont cause too much pain...


Some info on connecting PC to modbus: Modbus simulator, RS485/422

[TOTALLYRC]

Pulse direction = step and direction in most cases. You can't do motion via modbus. You could do the spindle vfd via Modbus.

Mike

[keebler303]

Pulse direction = step and direction in most cases. You can't do motion via modbus. You could do the spindle vfd via Modbus.

Mike

Correct. You can hook it up directly to mach as if it was a stepper driver. Just get yourself a breakout board and you are good to go.

Matt

[poldim]

Is the signal similar to PWM? What is the physical interface...2 wire?

A quick Google left me with a ton of parallel port breakout boards and then I found this one:
3 Axis Stepper/servo Motor Breakout Board,Cnc Mach3 Usb Interface Board - Buy Breakout Board,Mach3,Interface Board Product on Alibaba.com
Is it any good?

I suppose I could still control the spindle vfd over modbus, but that may be more complexity than necessary.

[keebler303]

Pulse and direction, more commonly referred to as step and direction or step/dir is the most common form of command from the control (mach3) to the motor driver. In a servo system, 1 step is generally 1 encoder count. If your servos have 2000 counts per revolution then every step pulse moves the motor 1/2000 of a revolution. The direction signal just allows you to take steps forward or backward. The step pulse train is a variable frequency with a fixed pulse time. The higher the frequency, the faster the motor will spin. The more pulses it receives, the farther it will go. You will have a step wire, direction wire and common wire.



Alibaba? You must be new at this. Please do some research here. There are hundreds (if not thousands) of threads here where guys are talking about what hardware they chose, if they like it, etc., etc. What are people using? Is it well documented? Does it have the features you need? Is support available?
You will find lots of people using cheap Chinese ebay breakout boards (BOB's) and many have no clue what to do with them because there is no support, no documentation, etc.
Here are a few sources popular to the users of this site:

CNC Break Out Board, CNC router
PMDX.COM - Products for CNC and motion control applications
CNC4PC

I personally either use these breakout boards, known as the "hillbilly board" or I make my own for certain applications as appropriate.

Ashburn Industrial Repair

I've never used any of the others at the above links but plenty have had issues with documentation. Here is one example, if you want to get into the nitty gritty of it: http://www.cnczone.com/forums/vertic..._build-21.html


Good Luck
Matt

[mike_Kilroy]

The Lexium was a private label of our Kollmorgen S600 drive. Just an FYI in case u want more information about them. it is capable of torque loop control, velocity loop control, and position loop control...

u need to understand the very different and basic difference between step/dir (or modbus or canbus too) & analog control of this or any other servo: it is MAJORLY DIFFERENT in philosophy and capability... google it and study it...

In summary, step/dir means your POSITION LOOP is in EACH INDIVIDUAL servo drive. Read that line again.... Hence you LOOSE a basic CNC capability: you will not get true circular interpolation - u can't - since no other axis knows what is happening real time with other axes. For this reason, this is the "poor man's CNC approach," or a really great hobby CNC.

On the other hand, analog command to the servo drives mean they get fed SPEED or TORQUE commands only, and the CNC controller DOES have full position control responsibility and does provide true circular and linear interpolation. Generally this means you pay another $ 1000 for a position controller that goes between the mach3 & drives, but it keeps the machine a true CNC rather than a hobby machine.

You need to know which you need for the work you will do and pick accordingly.

[Al_The_Man]

An example is such motion controllers is Galil Motion which use ±10vdc analogue control, calculate the motion trajectory internally are capable of electronic gearing and electronic cam features.
Dynomotion/Kanalog and EMC are also similar controls, which approach the capability of industrial CNC motion controllers.
Another advantage is that simple transconductance (torque mode) type amplifiers (drives) can be used, as the loop does not need to be closed within the drive, but back to the controller.
Al.