EAS slide, ARD-KD driver, Modbus: software overtravel alarm

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om_tech_support_JT
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EAS slide, ARD-KD driver, Modbus: software overtravel alarm

Postby om_tech_support_JT » Wed Dec 17, 2014 7:36 pm

Q: I have your EAS series linear slide and ARD-KD Flex driver set up to communicate with my own Modbus RTU software. I'm using my software to send Modbus hexadecimal commands to read/write to data register addresses. I'm using both FWD and RVS inputs to jog the motor forward and backwards. I turn them on with the 7Dh register. However, I noticed that when I hit the software overtravel limit, I cannot clear the alarm and jog the motor backwards away from the soft limit. I use the 181h register to clear my alarm. Do you have an example code somewhere for Modbus so I can see exactly what to send from my software to do this? Any advice would be greatly appreciated.

A: I have set up a test demo here and simulated your conditions with a Modbus RTU software. I was able to clear the software overtravel alarm. I believe the problem could be because of 2 causes which are listed below.

1. The overtravel action parameter was set to be "deceleration stop" by setting the 205h register to 1. 0 is for immediate stop. If so, the motor would pass the sensor while it's decelerating to a stop. When you jog the motor backwards, it would hit the limit again.
or
2. The FWD or RVS input was still on when the software overtravel alarm was cleared. To turn inputs off, set the 7Dh register to 0.

Here's exactly how I was able to clear the alarm from my Modbus SW after hitting the software overtravel limit:

1. I set my +soft limit to 500 for testing purposes.
2. I set 7Dh register to 16384 to turn on the FWD input only. This will run the motor at the programmed speed for Data0.
3. Software overtravel alarm occurs and stops the motor.
4. I turn off my inputs by setting 7Dh register to 0.
5. I set the 181h register to 1, then 0, to clear the alarm.
6. I set 7Dh register to 32768 to turn on the RVS input. It moves backwards.

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