Modbus Examples

[NicolaiL]

I'm looking to write an interface for my Daikin aircon system. It is communicating using MODBUS on an RS485 port.

The common registers are here:
http://www.realtime-controls.co.uk/p...20v1.06.00.pdf

However, I've not done any MODBUS stuff before so I was wondering if anyone had a couple of examples they would be kind enough to share to get me going?

Thanks
Nicolai

[enigmatheatre]

I'm looking to write an interface for my Daikin aircon system. It is communicating using MODBUS on an RS485 port.

The common registers are here:
http://www.realtime-controls.co.uk/p...20v1.06.00.pdf

However, I've not done any MODBUS stuff before so I was wondering if anyone had a couple of examples they would be kind enough to share to get me going?

Thanks
Nicolai

HI Nicolai,

It might be worth looking HERE:
Greig.

[NicolaiL]

Hi Greig

I did see that thread, but I can't tell when that plug-in will be out and rather than wait I wanted to throw something together for myself (plus enjoy the challenge at the same time).

Cheers
Nicolai

[timdotcom]

Hi Nicolail,

Modbus is quite simple.
A Master (homeseer PC) sends a request to a slave (Daikin) and the slave will respond with the requested info.

To integrate with Homeseer you can use a DLL which contains the Modbus functions.

http://www.modbustools.com/modbus_wsmbs.asp

But you need to be an scripting expert to write the script that utilizes the DLL.
Are you?
I gave it a try a while ago because i have a Modbus TCP PLC to control my heating system.
But i'm absolutely not an expert on scripting so i had to quit.

With kind regards,

Tim de Grouw

[NicolaiL]

Hi Tim

Thanks for the input. I took a look at the link to the DLL you posted and yes that does appear to simplify the communication considerably. However, the DLL has a $129 cost associated with it which seems a little steep for what I am trying to achieve (and anyone else who might want to use what I come up with).

I think the issue with MODBUS (having read up on the spec a bit ny now) is more that all communication is wrapped in packets which requires big Endian conversion and CRC checks and so on. So all doable, but obviously if there was any 'ready made' sample code for this piece then wrapping my specific unit around it would make this considerably easier.

Nicolai

[timdotcom]

Hi Nicolai,

If your interested i have the DLL files for Modbus over TCP.
Those came for free with my PLC.

It doesnt support Modbus RTU but you can always buy a gateway.
I know moxa has one.

Gr.

Tim

[cadillackid]

I have a modbus library.. however it is for VB6 and not .NET.. not sure if you can use it with VBScript or not?

I use MODBUS to communicate with the Blower speed control for my Zoned HVAC and wrote a VB6 program that runs alongside homeseer (didnt go the full route of a plugin).. and I just use the HS API to access data from HS.. I downloaded the library many years ago it was free online.. I can get it to you if you need it..
my 'AirCare" speed control uses RTU over RS485. I use a USB 485 dongle, my program and the library and it works great!.
-Christopher

[timdotcom]

Hi Christopher,

Do you want to share your library and scripts?
I`m looking for a way to get some data from my modbus devices and present them within Homeseer. (create a virtual device and present the value in HsTouch)

Gr.
Tim

[NicolaiL]

I have a modbus library.. however it is for VB6 and not .NET.. not sure if you can use it with VBScript or not?

I use MODBUS to communicate with the Blower speed control for my Zoned HVAC and wrote a VB6 program that runs alongside homeseer (didnt go the full route of a plugin).. and I just use the HS API to access data from HS.. I downloaded the library many years ago it was free online.. I can get it to you if you need it..
my 'AirCare" speed control uses RTU over RS485. I use a USB 485 dongle, my program and the library and it works great!.
-Christopher

Hi Christoper

That sounds like exactly what I need. If you are able to post it here or PM me a link that would be great.

Thanks
Nicolai

[NicolaiL]

Hi Nicolai,

If your interested i have the DLL files for Modbus over TCP.
Those came for free with my PLC.

It doesnt support Modbus RTU but you can always buy a gateway.
I know moxa has one.

Gr.

Tim

Hi Tim,

Thanks for the offer, but I did want to go RTU based on the devices I'm interfacing with. Looks like Christopher has something that would do the job.

Cheers
Nicolai

[janjanssen]

Hi Christopher,

I'm planning to connect a Fujitsu airco via the IntesisBox (www.intesis.com) to Homeseer via Modbus RTU.

I read you have developed a Modbus library for Homeseer (using a RS485 dongle). Would you be OK to share the interface?

Kind regards,
Jan

[beerguy]

I'm not looking to hijack this thread so I'll keep it to one post and create a new thread if it goes any further, but I'm looking for a basic primer or some simple software interface that I can test out on a modbus equipped boiler I just had installed. Unfortunately I got nothing from the manufacturer. If I can get it wired up to a PC is there anything that I can take off the shelf and poll the data in the boiler? I know nothing about modbus so even a link to an idiots guide would be fine. Thanks again and hope I didn't infringe on your thread.

Pat