gripper connected to my pc but can't communicate using modbus rtu protocal

newuhe 2018-01-11

my pc system is ubuntu14.04, ros version is indigo, and I used robotiq package to control my gripper using this command

rosrun robotiq_c_model_control CModelRtuNode.py /dev/ttyUSB0

however I received

AttributeError: 'ModbusIOException' object has no attribute 'getRegister'

I checked and found the issue is caused by this line of comModbusRtu.py in /home/username/catkin_ws/src/robotiq/robotiq_modbus_rtu/

response = self.client.read_holding_registers(0x07D0, numRegs, unit=0x0009)

this line throws 'ModbusIOExcption'.

I don't understand why it happens, I check my usb port with

dmesg | grep tty & lsusb

and get

[2483608.973947] usb 1-13: FTDI USB Serial Device converter now attached to ttyUSB0

Bus 001 Device 005: ID 0403:6015 Future Technology Devices International, Ltd Bridge(I2C/SPI/UART/FIFO)

and the LED in gripper is always red, however when I connect the RS485 to usb cable of gripper to ur robot controller, the LED turns blue and I can control it using polyscope.

Can anybody help me figure the issuem, I'm really confused.

carlosjoserg 2018-01-14

Hi @newuhe

Saw your post on github as well.. did you make sure you have write access to the USB port?

You can do it temporarily with something like:

sudo chmod 777 /dev/ttyUSB0

And you can add permanently with:

sudo adduser YOUR_USER_NAME dialout

newuhe 2018-01-15

I'm absolutely sure I've done all you mentioned.

carlosjoserg 2018-01-15

Don't know what else it can be then. If you want, we can set a skype/hangout and try to figure out whats happening. Let me know.