I want to get the energy readings from 50 Energy meters in surrounding of 1KM to a PC. How can I do that? What will be the minimum time it will take for 2 consecutive readings in a energy meter If I have to go for Current, Voltage, Power factor, Power, energy from single meter?
I'm beginner in this field of networking. Also please inform me about same type of systems used in diff. places.

 

U can try using RS485 multidroping network, speed depends on the baud rate u set for the network. This type of network may use 38.4 kbps of speed.

 

This really depends on the meters - both how fast they response to requests & what the worst-case slow response time is. My best-guess rule of thumb is don't expect more than 4 Modbus polls per serial port per second (unless testing proves otherwise).

So you could use 50 serial ports - 1 meter per port and lost of cables to poll each a few times second.

Or you could add enough RS-485 repeaters and cabling to have 50 meters one serial port be very lucky to get 1 poll per 15 or 20 seconds. But given errors and timeouts, you'd be lucky to get 1 poll to each per minute.

So you'd likely best use say 8 serial ports and group the meters with 5 to 7 per port. You could also use 8 Modbus Ethernet/serial bridges to gain some multi-master access. Spliting the 50 up like this will more likely give at least 1 poll every 3-4 seconds.

- LynnL

 

Depending on how much data, the speed required and the type of meter, you can convert the serial signal to another medium (e.g. Ethernet, PSTN/GSM/GPRS/EDGE, even WiFi/Radio).

On the server side you can use your existing legacy software with virtual COM port redirectors to poll these converters for meter data.

Check the note at:
http://www.multenet.com/industry/power.html

-Multenet Techsupp.