Universal Robots Forum

End-effector communication

We are currently developing an URCap for our end-effector and we are wondering whether there is a clean configuration for our needs or whether we have to add an external cable to communicate with the device, which is a bit annoying.

We can power the end-effector with just the two pins of the Tool Connector (24V DC and GND), i.e. 600 mA is enough. The problem is the communication with the device since we exploit the RS485 protocol to send commands and read sensor measurements. The other six pins seem not to be designed for communication protocol, even if we could implement something similar using TIs and TOs. Nonetheless we are a bit confused:

  1. Would it be fast enough?
  2. Can we shortcut any of the DI/DO to TI/TO? (a sort of remap of the Tool port)
  3. Is the Digital Output voltage configurable, i.e. from 24V to 5V when it is ON?

If none of the above questions are feasible, the only solution seems to be an external cable for the communication, which it is fine for developing and testing, but a bit frustrating for a commercial application. Is there an other solution that we haven’t thought about?

Thank you for your assistance,
Alessandro Tondo @qbrobotics

@alessandro.tondo

The digital in/outs cannot generically run RS485, neither can the pins be re-mapped to other channels.
However it might be possible by bit banging to generate a robust communication protocol.
The scan times for the I/O’s is quite low, so the protocol would need to be very lean and could also include analog input feedback.

The tool voltage can be set discretely to either 12 V or 24 V.

Wireless communication might be another option, however is very noise dependent.

Thank you for the info, Jacob.

Actually I believe that 40ms to send a single bit would lead to a very slow communication protocol. Anyway, if we come up with something useful we will share it with the community.

Alessandro Tondo @qbrobotics

Hi, pros
When you say wireless communication how do you implement a WiFi communication with esp8266 module. If you have guide please share one.
Thank you

If you connect a wifi bridge to the robot, you could just use an ESP8266 to connect to that wifi, then use the modbus protocol to communicate with the ESP8266, if you just need to control more inputs and outputs than the tool connect or allows.

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I believe external cabling or slow bit banging would be a more reliable choice, considering the electrical noise at most factories.

That being said a solution with a pair of ESP8266’s would be quite sleek.
Note though, that the controller have no serial connection and no 3V3 outlets, so you might need a Pi or a more industrial device to convert from Ethernet to UART and a 5V USB outlet to 3V3.

I guess there is an ADC in the tool to read the analog inputs. Which resolution does it have? I thought about creating an interface with it to get (part of) the FT300 Data after reading it with an Arduino or similar.