How to read the response from slave?

Hello,

I am also stuck in communication between BTU meter model  Scylar INT 8 with Siemens controller. I am new to M-Bus and would like to know how to read the response from slave like how many bytes of data the slave has sent in response and how to identify the instantaneous parameter values sent by slave in CI field. 

We need the address of the instantaneous values like flow rate , temperature etc. of this BTU meter that needs to be put in Xworks for programming. From where can we get these addresses of the above parameters.

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Split from UH50 Series Heat meter and M-Bus.

Hi Aameet,

before I 'll go deeper with Mbus, can you please provide more details about your solution?

What I'm not sure, which Siemens controller do you think to use for integration of the meter.

There is more ways to integrate:

1. PXCxx + TXI2.Open - more cost effective solution

2. PXC001 - integration controller 

3. ???

Acc. choosen controller can be advice more detailed solution .

BR

Cuhalovjan

Hello Cuhalovjan,

    Thank you for your response. 

     Customer is having TXI2.open to communicate with BTU meter. I understand if the Master sends telegram to BTU meter then it would respond back with feedback that would look like:

"68 Lfield L field  68  control Field  Address  CI Field  User Data in bytes  Check sum  16 “ .

Here the ' User data in bytes ' will have information of parameter values. We wish to know how to decode this byte data like how many bytes and which parameter in the sequence. 

After decoding this , how the same can be integrated through TXI2.open.  What values or address would the TXI2.open require to decode the above response from slave. 

Manual of Scylar 8 attached herewith. It has got VIF values of various parameters and I suppose those can be used to decode the parameters. 

Hi,

You can use a program called MBSheet to scan the MBus network for devices, and then get a read-out of the point-mapping within them.

For the integration, I think maybe you're 'over-thinking' the requirements . If the mapping is done correctly, the system (TX Open) will decode / translate all responses for you.

The data sheet you attach shows the MBus addresses in Hex format. Entry into the TX-Open tool needs to be done in Decimal format. See HERE.

See attached as an example, Meter1.JPG - although it's for Modbus, the principal is the same.

Meter2.JPG shows part of the data entry within the TX Open tool.

Bear in mind you will need an MBus power supply, in addition to the TX Open module.

Also, for the CI points within the PX - these need to be configured for 'Metering' on one of the Input pins (from memory, the pin defaults to 'Counting').

Regards,

I would like to recommend to you to do a scan with TXI.Open modul and TXI:Open tool - there is feature "MBus scan" and the result can be then downloaded from TXI2.Open.

This scan will be very help full together with information about, which values you are interested.

Then I can try to take a look to the scan and try to prepare a template for your meter. 

It can be used as well some 3rd part program for scan MBus.

Hello Cuhalovjan,

     Thank you for the further inputs. 

We have asked the customer to read the BTU meter with MB sheet and that will be possible. The concern over here is again how to address this device in controller's program. You have shared one attachment of Modbus addressing where parameter register addresses like 30000 , 30002 etc. were mentioned. Usually these register addresses are available in device's manual.

I agree in M-bus there will not be address similar to Modbus and it would be different. But then how to map BTU meter's parameters in controller. We are supporting the customer who is trying to integrate the BTU meter with TXI2.open converter. 

Is it possible to get the BTU meter's mapping details from MB sheet ? 

Thanks,

Hi,

aameet

...You have shared one attachment of Modbus addressing where parameter register addresses like 30000 , 30002 etc. were mentioned. Usually these register addresses are available in device's manual...

The attachment (Meter1.JPG) I provided shows the last digit of the decimal address as being highlighted in yellow - this was meant to provide a simple correlation between decimal and hex.

You already have the mapping table for your Meter - it's in the Meter PDF you attached in your second post above. You need to convert the Hex addresses to Decimal for entry into the TX Open tool. 

The address formatting for the TX Open tool is provided in the other attachment I provided (Meter2.jpg), i.e. 2;-1;-1;-1 (where the 2 is the decimal address of the MBus point).

An example - from your Meter PDF, if you take the Flow Rate at a resolution of 1 m3/h (page 18), the Hex address for this is 0x3E. This is 62 in Decimal format. In the TX Open tool, this point would be addressed simply as 62;-1;-1;-1.

If you're still not sure, scan the network live with your tool of choice (MB Sheet or TX Open tool) and see what results you get.

Regards,

Hi,

it wasn't me who shared the document with ModBus addressing.

I can share the engineering document for TXI.Open, where is visible how to do it.

But first you have to have a scan from meter (best from TX.Open tool) and then I can provide more detailed advice.

@Cuhalovjan  & @ _CJ ,

Thank you guys for your valuable inputs. We have established the communication and the problem is solved now.