Hey guys,

I have a project I'm working on by myself, which is a small robot which drives around and avoids objects using IR sensors and Dual Ultrasonic Sensors.

I have a network of 3 Dual Ultrasonic Sensor units which are daisy chained together using RS485. RS485 utilizes RS232 protocol, am I right?

Anyway, I manually address each of the units using my microcontroller to say 0x11, 0x12 and 0x13, for example. When the units are connected to the microcontroller individually (not networked), they behave well.

When I daisy chain two together, they are also fine... But when I connect 3, the third always works intermittently or just dropps out completely returning a packet of straight zeros every time.

Could you guys give me some troubleshooting advice?

Thankyou muchly.

Andrew

 

We need a schematic with part numbers.

hgmjr

 

All I have is this datasheet:

It doesn't have a schematic, unfortunately.

 

I think he means a drawing of how these sensors are wired into the microcontroller, and all the supporting components.

Did you just wire it up a little at a time and NOT use or have any schematics to follow?

 

Umm.. Not really.. Sorry!!

It just goes like this:

Sensor1 --> Sensor2 --> Sensor3 --> Arduino (using ATMega328P + expansion board)

I plug the output of Sensor 1 into the input of Sensor 2, etc. There is no circuitry made by me.

 

It would still be better if you could supply us with a diagram. A picture being worth a thousand words was never truer than in electronics.

hgmjr

 

Wait for a little bit and I'll put my photoshop skills to the test =) I'll post again soon.

 

 

Wiring between the Arduino RS-485 shield and the networked ultrasonic sensors must be correct for this to work.

You will need to provide us with a detailed wiring diagram of your connection for us to help you out.

Also it would be helpful if you give us the part number of the Arduino RS-485 shield you are using.

Eventually we will need to see your Arduino program to make sure that you are conforming to the communication protocol outlined in the datasheet for the ultrasonic detectors.

hgmjr

 

Hello,

Do you also have the jumpers set as stated in the manual?

Communication LED：As the device is powered up, this LED will flash four times which indicates that the sensor is working properly.
This LED will also flash when it is communicating with other devices.
Jumper A：Not in use
Jumper B：When the sensor is working under a network, only the Jumper B for the first Device and the last Device need to be bridged.

Bertus