Multi function meter looping

Hi,


we have to design system for Energy monitoring system.


We have 70 Multifunction meter in a different-different location we have to take data over SCADA ,and all multifunction meter are equiped with modbus RTU(RS-485) protocol.


we have to take data over the SCADA through PLC AC500


distance between one meter to another is approx 90 meter.


my question is


1-how many meters will be looped in a single loop


2-is required PLC for every loop or we can use one plc for all meters


By kstoilov on 5/5/2018 | Like (0) | Report

Is it other post here answer to your question? It is a matter of planning of your RS-485 network, then most probably only one RS-485 port in AC500 will be enough. But I could suggest to plan 2-3 ports in the PLC, it is not so big cost


By Pinetree on 5/7/2018 | Like (0) | Report

Has anyone here done a RS485 daisy chain connection 1km long?
I haven't, but I think that you will needing thicker wiring specific for designed for RS485 and might risk problems on line termination resistors to resolve signal reflection.
And you will be needing at least 7 of these if not more.
70 Multimeters at 90m distance from each other, if they are all in a long daisy chain that comes to 6300 m.
All need to communicate in one control room, so each loop header (whatever you choose) would need its own very long communication lines, you will be considering repeaters.
I think you need to research on the installation site, you might need to consider a fiber optic backbone, with fiberoptic/RS485 converters.
The number of converters and the number of instruments on the RS485 side, should be calculated according to the cost of converters, cable costs and labor.
In a country with high labor costs, you might find it convenient to have an Fiber optic/RS485 for each meter.


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saffu   

asked 18 days ago
Closed



Best Answer

1

Hi,

Theoritically for modbus you can connect upto 250 slave devices that also depends on the typeof master (PLC) that you have selected. This answers your first question.

2nd is with modbus you can go upto 1.2kms of length (single Loop). Beyond this their will be the voltage drop in the signal srength.

I hope this is usefull to you.

Yoginder.K.Singh   

answered 17 days ago


 


Add New Comment


Answers

1

Hi,

Theoritically for modbus you can connect upto 250 slave devices that also depends on the typeof master (PLC) that you have selected. This answers your first question.

2nd is with modbus you can go upto 1.2kms of length (single Loop). Beyond this their will be the voltage drop in the signal srength.

I hope this is usefull to you.

Yoginder.K.Singh   

answered 17 days ago


 


Add New Comment


1

Hi,

You can use MODBUS RTU to MODBUS TCP/IP converter. Refer my attachment.

Kindly consider following things:

1.Distance: max 1000 meters

2.Topology:daisy chaining

3.Baudrate : selection based up on distance .for 1000 meter 9.6kbps.

4.Number of slaves : 32

kindly seperate power cable and communication cable.

 PLC_ILPH.PNG

vigneshwaran92rce   

answered 16 days ago


 


By Pinetree on 5/7/2018 | Like (1) | Report

Has anyone here done a RS485 daisy chain connection 1km long?
I haven't, but I think that you will needing thicker wiring specific for designed for RS485 and might risk problems on line termination resistors to resolve signal reflection.
And you will be needing at least 7 of these if not more.
70 Multimeters at 90m distance from each other, if they are all in a long daisy chain that comes to 6300 m.
All need to communicate in one control room, so each loop header (whatever you choose) would need its own very long communication lines, you will be considering repeaters.
I think you need to research on the installation site, you might need to consider a fiber optic backbone, with fiberoptic/RS485 converters.
The number of converters and the number of instruments on the RS485 side, should be calculated according to the cost of converters, cable costs and labor.
In a country with high labor costs, you might find it convenient to have an Fiber optic/RS485 for each meter.


By kstoilov on 5/7/2018 | Like (0) | Report

Hi, it is very good comment. The question needs very deep investigation, planning and calculations. In similar post I made remark that 1200 m for one chain is a theoretical value only


Add New Comment



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