BTR instruction and a micromotion flow meter

lbric

Member
Join Date
Jul 2013
Location
Bell Gardens CA
Posts
27
Hello,

I have a quick question hoping to get some clarity. I am working with a RSlogix 5 program where a PLC5 processor is communicating via modbus to a micromotion flowmeter. I have worked with the MSG instruction (ML1100 w/micromotion) and its very clear how that instruction is setup to select what type of register to read from the flow meter, how many registers to read, and where to place them within my program.

the program i am working with now is using a BTR instruction but for the life of me i cannot figure out what is going on. In the uploaded file rung 30 has the BTR instruction. what i understand: the control block has the status of the instruction, the data being read will be stored starting at n9:93 and will store a total of 62 values. what i don't understand: what registers are being read? where do you specify what registers you want to read? i opened up the setup for the instruction and can only make sense that it shows you the data being read stored in the data file registers. I guess i have the same questions on how to write using the BTW instruction.

if someone can shed some light on this it would be greatly appreciated. This forum has been one of the best learning tools i have come across and just appreciate how people take time out of their day to help others.

thanks,
Ricardo
 
Ricardo,

Is this a new install, something you're fixing/modifying or simply a learning opportunity? I've not used a 1771-SDN before, and I have no Modbus experience but have plenty of block transfer experience.

It makes sense that BTW will have the configuration info telling the meter what to put into those 62 words of data & where they go. If there's no BTW needed, then it seems like the meter has a fixed configuration. Either way, the Micromotion manual should be key to getting this configuration map.
 
do you have a copy of a software package named RSNetworx for DeviceNet ? ...

and can you find a file with an extension of DNT ? ...

I'm just GUESSING without seeing ALL of your system - but the basic idea is that your 1771-SDN DeviceNet Scanner module has been programmed (set up) with a "scan list" which identifies the specific locations that you're asking for ...

if you can find the DNT file, you can post it here (as an attachment to this thread) and someone here should be able to open it and show you what's going on ... you'll have to zip the file in order to post it (forum rule) ...
 
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since we haven't heard back from you - I guess we can assume (gosh I hate that word) that you've got it all figured out ...

but if not - the SAMPLE figure below might give you an idea of the type of information that you're looking for ...

your system will definitely be different - but at least this may show you what the RSNetworx for DeviceNet software looks like ...

the basic idea is that the RSNetworx for DeviceNet software is used to "configure" the network - in order to "map" the data into the desired memory locations in the PLC's data tables ...

good luck with your project ...
.

DNet_Sample_B.PNG
 
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