I’m trying to use Xbee to remotely control my servo bought from lynxmotion. I get two Xbees, one on the LSS adapter board which is connected to the servo, and the other is connected to my computer. I configured the two Xbees with XCTU, but when I tried to send the commands, the servo didn’t work as without the Xbee.
For example, previously, I wrote #0D100\r to let the servo rotate to 100 degree. Now I typed the same command, which was then converted into ASCII by XCTU, was sent to the xbee on the adapter board (I saw the RSSI light was on until the messages were all received). However, the servo didn’t do anything. I’m wondering if there’s anything else needed to be sent to the adapter board in this case.
I also tried to send #0D100\r directly in LABVIEW, but the same thing happened – the RSSI light was on but the servo didn’t rotate.
By the way, the servo worked well in usb mode when I directly connected it to the computer and programmed it in LABVIEW.
Before connecting the LSS, it might be a good idea to insure that the communication between the 2 XBee modules work as it should. To do so, you could perform a loopback/range test.
After confirming that the 2 XBee modules can talk with each other without problems, next step would be to verify the baudrate:
What is the baudrate configured in the LSS ? (By default, the LSS comes with a baudrate of 115200)
Did you configure the baudrate of your XBee modules to match the LSS baudrate ?
BTW, a baudrate of 115200 seems to create a communication issue between an XBee and its host. This has been discussed in this Digi forum post.
If that’s the case, we suggest you to try a baudrate of 9600. To do so, the XBees need to be configured through XCTU to changer its baudrate.
As for the LSS, please take a look at this Wiki link explaining how to change an LSS baudrate.
Hello,
Thank you for your response. I performed the range test and the package sent by one Xbee module were all successfully received by the other, so I guess the communication worked well. The baud rates are already set to be 9600 for all three devices at the beginning when I tried to make the two XBee communicate. Would there be any other possible causes of this problem?
Also, am I supposed to send the same command in LABVIEW as what I did when the LSS is directly connected to the computer via USB, or is there anything I should add or change when communicating via XBee?
Thank you again for your help.
Please perform a factory reset on the LSS using the button by following the button menu available here .
Please double-check that the LSS works as it should through USB (LSS Adapter switch on USB mode) and that it has the correct ID. We suggest to use a simple command as querying the LED value for example. The command to query the RGB LED color for an LSS with an ID 0 is: #0QLED\r
If the ID and baudrate are correct, the LSS will reply with a number corresponding to the LED color (for example: *0QLED0\r). Here is a link to the Wiki for more information about the LED command.
Try to communicate with the LSS using XBee. If it still doesn’t work, could you probe the local XBee module Din and Dout lines and the remote XBee module Dout line (using a logic analyzer or an oscilloscope) ? Again, we suggest to send a simple command as changing the LED color of the servo (ex: #0LED2\r)
Please attach pictures of your complete setup and logic analyzer/oscilloscope screenshots
Hello. I’ve reset the LSS and double-checked that it worked via USB. The ID is correct and the LED light color is white which is normal. I don’t have a logic analyzer or an oscilloscope for this project right now because I’m not in the lab, but I’ll think about it later. Here are the pictures of my setup.
I’ve also tried encoding my command with ASCII, HEX, and some other similar things but it still didn’t work. Another thing I’m confused about is that my XBee seemed to communicate via ASCII code by default because the time needed to send a command like “#0D100\r” took about two to three seconds (the light was on at that time). It should be really fast if it’s not sending the ASCII code frame by frame. I’m not sure but I guess a reason can be that the XCTU software used to configure the XBees send my command via API frames.
Thanks!
You can connect a 5V USB to UART Adapter board Rx pin to one of the LSS Adapter Tx pins (without forgetting a common ground between the two boards) and using a serial terminal software as Putty, you can sniff on the the LSS Adapter Board/XBee host module Tx line and see what commands are being sent to the servo. In case you don’t have a USB to UART adapter board lying around, you can use an 5V Arduino board (like an Arduino UNO).
