Energy Meter Communication

[funfrok]

Hello everybody, I am currently working for a project where we will read energy usage,current,voltage data from energy meters using RS485. Energy meters use IEC 62056 (IEC 61107) protocol. I have success reading from energy meter, but it takes too long. It takes 14 seconds to read 3 current values from a energy meter, and there will be 16 meters in rs485 bus. We are using C protocol, manufacturer says C protocol can be used and communication is made in programming mode. The protocol starts with 300 baud, and speed can be switched to higher speeds (4800-9600). But when i switch speed, parity problems arise (first 3-4 characters of message) and BCC is wrong. Is there any tools that i can test this communication protocol, i couldn't find any freely available tool. Manufacturer isn't helping at all. Does anyone have background on this subject, do you have suggestions. Thanks

[BobLfoot]

IF I remember correctly RS-485 can be "sniffed" with a laptop, hyperterminal and pair of wires. You connect the RCV pin of your rS232 port to one lef or the other of the RS485 data and use hyperterminal to capture the stream. I also PM'd a couple of more netowkr savy friedns, hopefully you'll hear from them soon.

[P Daniil]

I would first check the basics of RS485: the terminations, the cable type and length and that all meters are communicating at the same baud/setup. With large lenghts or noisy environments, galvanic isolation is also desirable. For EIA(RS)485 basics you can look up application notes/documents under "RS485" at the TI site or any other similar manufacturer. Working at 9600 baud should be no problem with cable lengths up to 1000 m (3000 ft). BobLfoot's "snif" works fine with short cable lengths, near the terminations and at the risk of ruining your PC if the RS485 bus is at a highish or unknown potential relative to the PC's ground (I have found this the hard way!). For diagnostic "all-weather" work, use any commercially available EIA(RS)485/EIA(RS)232 galvanically isolated interface. Of course, if you are the DIY type or want to get your hands busy with a soldering iron, you can also roll your own interface circuit.

[BobLfoot]

It was early morning {late night for a third shifter} and P Danill is correct I forgot one warning use you laptop on battery power and ungrounded. Do not try "sniffing" with a desktop pc or a laptop running on a power adapter. The ground loop can fry a nice piece of hardware.

[funfrok]

Thank you very much for your answers. I am using a protocol converter so sniffing traffic isn't a problem. But there is no operational reader to sniff, i am sniffing my own traffic for control purposes. We have a new energy meter now, which i have communicated at 4800 bps without a problem using a pc. The old one had some bugs i guess. Currently working to do the same with Mitsubishi Q PLC. If anyone has experience about IEC 1107 / 61107 / 62056 i'm open to share knowledge.