from the Has anyone used Bluetooth for Modbus communications? department...
Bluetooth for Wireless Modbus
Communications systems and equipment. topic
Posted by Per-Erik Svensson on 26 August, 2003 - 4:00 pm
I have a project where I would like to use Bluetooth for communication between a laptop and a Telemecanique PLC running Modbus RS485. The laptop has integrated Bluetooth that I would like to use. Can anyone guide me?

Posted by Kelvin Proctor on 28 August, 2003 - 12:24 am
Your best bet would be to get a Bluetooth serial port adaptor. (similar to the common serial-to-ethernet adaptors available all over the place) With a proper driver this will then appear as just another serial port on you local machine (like COM1). You can then use 'normal' old Modbus comms software.

Most of these device will be designed for RS232, so you may need an RS232 to RS485 adaptor in line as well.

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Posted by R. Dutra on 28 August, 2003 - 3:25 pm
You can try Connect Blue at

They have a serial port adapter (RS232/422/485) that you can connect to your PLC.

Hope this helps.

R. Dutra

Posted by Marc Sinclair on 30 August, 2003 - 4:40 pm
Brainboxes manufacture a bluetooth serial replacement module which might be of interest

Web: * <> _*

Posted by Lynn at Alist on 30 August, 2003 - 6:16 pm
Just a side note - there is an effort in place to "standardize" how Modbus is encoded into Bluetooth. I'm not a bluetooth expert, but it has to do with how one "maps" an 8-bit RTU address and MB/TCP header into a Bluetooth Master/Slave network limited to 7 slaves per Master. I know both ConnectBlue and are involved. At present some vendors just "tunnel" MB/RTU into bluetooth & assume only the addressed RTU slave answers, while others create a simple sub-header to allow more efficent direct comms.

My main interest (of course) would be to allow a MB/TCP "bridge" to exist that just happens to have a mix of MB/BLU and MB/RTU clients/servers underneath. Seems BlueTooth includes enough richness that a MB/BLU client could even give direct IP info to my bridge and function like a true MB/TCP client. I made up the term "Modbus/BLU" - not sure what they plan to call it, but I like short names.

I haven't been able to find an official path outside of joining the BlueTooth Org to contribute on this yet - their plan is an ISA working group.

Best Regards - LynnL,

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