Serial / usb to serial port troubleshooting

Jim. Thanks. Have ordered another controller from Active Robots. Will test on my return on June 29th. Will send the one I have now for testing too.

Just FYI: The Sparkfun 5V FTDI Serial USB adapters work with the SSC32.

I am using SSC-32, AL5D arm and serial to USB adapter from Lynxmotion and started from this power configuration:

  • separate power for the SSC-32 board (wall power 7VDC)
  • VS1=VL jumper removed,
  • 5V from PC (the PC, connected via USB-serial to SSC-32) for servo powering
    And all OK with it, all works fine!

BUT

When I obtained 6V DC separate wall power supply, I can’t get answer from SSC-32 even to my ‘ver’ command. Configuration is:

  • separate power for the SSC-32 board (wall power 7VDC)
  • VS1=VL jumper removed,
  • 6VDC from wall power for servo powering

I found out that even without servo powering:
If I connect ground from my PC to the VS1 servo ground – all OK with communication.
If I disconnect this ground, I have not answer from SSC-32 to my ‘ver’ command.
When I connect ground again - all OK again.

Any help will be appreciated.

Generally speaking, unless you have done some additional wiring, I don’t think this should be happening (but I don’t have a Lynxmotion adapter, just the usual cheap ones). You probably need to disconnect the ssc-32 from the computer and then trace out the power for VL and VS to see where the power issue is.

I have done it and now I see:
Power config:

  • separate power for the SSC-32 board (wall power 7VDC)
  • VS1=VL jumper removed,
  • NO ANY other power (VS1, VS2…) connected
    If I join shield of the SSC-32 serial connector with the SSC-32 ground - I have correct reply after ‘ver’ command and all ok.
    If I disconnect this join, I have not answer from SSC-32 to my ‘ver’ command (sometimes ‘Processor Good LED’ shows that SSC-32 receive data from computer, but it seems computer can’t get answers from SSC-32).
    I’ve checked it on the two different computers with the same result.

I see that ONLY #5 pin of the serial connector on the SSC-32 joined with the SSC-32 ground. BUT USB to serial adapter has not ground on this pin!

Should I permanent connect shield of the SSC-32 serial connector with the SSC-32 ground?
Which could be disadvantages at this decision?

Going to need to see some images of your wiring in order to help. From your description it should not need the connection.

Ok, remove the wire from DB9 shield and PC case. Put a volt meter on the VL terminals right on the board, meter leads direct to the tops of the screw heads. Tell me what you see. 7vdc?

I’d check to see if the solder connection between the ssc-32 db9 pin #5 ground and the ssc-32 ground trace on the board is broken or bad.

Yes, exactly 7VDC from laboratory power supply, and green LED lights after power on.

This connection ok, but as I written there is no PC ground on #5 pin of the USB to serial adapter.

Ok I have read through this again from the beginning. So the board powers up fine but will not receive commands, right? At first I was thinking it was a power issue. But I now see you are saying the USB to Serial has no ground. I checked one on the shelf and it does have a connection from USB shield, DB9 shield, and Pin 5. However note there is no ground connection on the DB9 shield on the SSC-32. It’s only ground connection is on pin5. This is probably an effort to eliminate ground loops, and is not a problem. It’s looking like the USB to serial is the culprit. As you mentioned you can just make the ground connection and you are up and running.

I disassembled my new UC232R-10 USB-Serial Adapter and yes, I have found the wiring track on the board from the general ground and pin #5 of the DB9 RS232 COM connector.
Unfortunately this wiring track has defect. As a result I have not PC ground on the pin #5 and this FTDI Chip product doesn’t work proper :frowning:
I’ve restored this wiring track on the adapter board and all works fine now.
It’s a very pity that FTDI Chip doesn’t test its products properly.

Anyway thanks all Lynxmotion guys for the quick help!

Good find! I’m glad you got it working! 8)

My robot doesn’t seem to work at all.

It was working fine this morning. Then I put it away in the box. I took it out of the box to start working on my project, it isn’t doing anything. I am so tensed. Someone help me. There is no power to the robot. Seems like the adaptor is working fine. What else can be the problem.

Is it the SSC-32 circuit box?

I need help in sorting it out. I will be doomed if I can’t get it working. Somebody please help me.

Hi listedunlisted,

First thing you need to do is start your own troubleshooting thread. Please provide much more information. You didn’t even tell us what kind of robot it is… Please use part numbers and provide much more detailed information.

I am sorry. It’s a Al5A robotic arm. I figured out the problem and I fixed it. Hopefully it doesn’t happen.

Hi,
I recently (2 weeks ago) purchased a new SSC-32 Ver 2.01, it came with the Atmega 168 processor.

Problem:

  1. I am not able to get communication established between a computer and the SSC-32. The green light D1 turns on and stays on even after all my attempts to communicate with the device.
    I have tried this on two computers, using Win7, and XP (specs below) – I have also used 3 different DB9 cables.
  2. Photograph taken – can’t post for 24hours per your upload policy for new users. I’m happy to e-mail if you like.

Repro Steps:

  1. Connect 9v power supply to VL (confirmed 9v power)
  2. Connect 6v power to VS2 (jumpers VS1=VS2 both jumped vertically)
  3. BAUD jumpers set to 115200 (both installed vertically)
  4. TX RX jumpers both installed (both installed vertically)
  5. Connect Serial cable between SSC-32 and Serial port on PC (COM1)
  6. Turn on power (both at the same time)
  7. Launch LynxTerm
  8. Click All 1500, and All 0 [result: nothing happens – and green light stays on]
  9. Click disconnect – and check communication settings (115200, 8data bits, 1 stop bit, no parity, no flow control)
  10. Confirmed system com1 settings are the same (115200,8-1-none-no)
  11. Click connect
  12. Type in ‘VER’ [result – nothing… and the green light stays on – never flickers]
  13. Click on the Reg button – dialog saying ‘can’t fine SSC-32 card’ comes up.
  14. Click on the Firmware button – dialog showing nothing in the version field comes up.

Computer 1 Info (Desktop)
• DELL T-3500 Desktop
• Windows 7 (all current patches)
• Serial port / COM1
Computer 2 Info (Notebook)
• Compaq Evo N410c – Notebook
• Windows XP
• Serial port / COM1

Project Info
• Attempting to control servos via DB9 serial output from computer.

Image/Video Info
• Will provide once I can upload them (new user cannot upload photos for 24 hours)

Thanks much,
Bruce

The quick test is to jumper the tx and rx pins on your DB9 cable and see if what you type into lynxterm is echoed back to the lynxterm screen. Other things to check is to look at device manager and see if the comport has the same number you are using.

The LED will go out when you send data to the serial port. This will happen even if the data format and baudrate is wrong. My guess is there is a problem with the SSC-32 if two computers can’t make the LED go out. Can you send the SSC-32 in to us?

Thanks for the responses - I jumped the tx and rx pins and what I type in is echoed in the terminal. And the com port checks out as well. I attached a picture just in case there is an end user setup issue.
Unless you see anything wrong with my setup, I’ll send the board in. - Thanks