I cannot conect to CHR Serial Interface

[Heriberto]

Hello, I am trying to connect my device UM7-LT to CHR Serial Interface, but I cannot. The program tells me:

– Error: Timeout while communicating with sensor.

I have followed the tutorial video, but the problem still continues. What could be the problem?

[Caleb Chamberlain]

1) Make sure that the serial settings are correct (port, baud rate, etc.)
2) Make sure that the UM7 is connected to your computer properly (through a USB to logic-level UART converter, or an RS-232 to logic-level converter). Make sure that whatever level translation device you are using shares a ground with the UM7, and that the UM7’s RX goes to the converter TX pin, and TX to RX.

[Heriberto]

Yes, the serial settings are correct. I connect the UM7 through the cable TTL-232R-3V3 of FTDI CHIP.
With this cable I can receive the measures in the hyperterminal or in a program like Docklight, but I cannot connect through CHR Serial Interface.

[Caleb Chamberlain]

If you can receive correct data through another terminal program, then the Serial Interface should work without any problems. Have you modified the baud rate or any of the data transmission rates on the sensor?

[Heriberto]

I have not modified any configuration. In the other terminal program I use 115200 8N1. I try send a configuration to UM7 through terminal program and I do not receive answer with the COMMAND_COMPLETE, but the measures realized, yes, I receive it. And I do not understand why it occur.

[Caleb Chamberlain]

The Serial Interface will attempt to send the command 3 times before giving up. If the UM7 is receiving the packet (as evidenced by a behavior change), then somehow the acknowledgement packets are not making it to the serial port. The only condition in which I’ve seen this happen is if the bus is swamped with too much data (because the baud rate was dropped or lots of data transmission is turned on) or if the serial conversion hardware can’t keep up.

An FTDI board should be able to keep up if it is functioning properly and designed correctly. We can’t vouch for other hardware, but we do know that our serial expansion works well: http://www.chrobotics.com/shop/usb-expansion-board

[Heriberto]

OK, thak you very much!
Could I restore the factory settings the device? I know that with register “RESET_TO_FACTORY” (0xAC), I can restore the device. But like I do not receive a response, I do not know if it has made. Is there another way?

[Caleb Chamberlain]

A reset to factory should work, although if you don’t ever receive a response, it could be that the baud rate is being changed (the serial interface doesn’t know when the baud rate is being changed, so you’d have to reconect).

[Heriberto]

OK, thank you very much for answering me. I am going to analyze the hardware that I use, and I will change it if it is the problem. If I find out what the problem is, I will let you know, and so, it may be considered for other consumers.

[Michael]

As soon as I detected this site I went on reddit to share some of the love with them.

[Author]

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