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« on: February 15, 2010, 12:44:18 PM »
hello Guys,
When in peril I always turn to the knowledge of our beloved group.
I just need some insight on some thing that came to mind and was thinking of how to do it.
Imagine, in a small scale, a pick and place machine, that can go and pick anything from a 3x3 grid, there is a PC as a user interface, where the user selects which item from the 9 on the grid he wants and then the 3 axis + gripper goes to that coordinate and picks the item.
I was thinking of using a PLC to control the pick and place (DL06) with high speed outputs to move stepper motors. I was wondering how can a PC communicate with the PLC, i believe it is through Modbus RTU, and from what I have been reading you can just send a hex string trough the serial port to do this, is this right? for example:
1 06 0001 7D0 9A9B
where 1 is the slave address
06 is the function code to preset a single register
0001 is the #40002 register i want to write to
7D0 is the value of the position i want to sent the pick and place to in the x axis (2000 in decimal, as in 2000 steps)
9A9B is the cycle redundancy check
Am I on the right track?
Then I can send that 40002 register of value 2000 to step counts on the high speed outputs of either the PLC or an expansion module.
Can anyone point me to a good resource for this kind of information?
Best regards
Fernando