EKM Metering

Hi,
I'm trying to communicate with V4 meters through an iSerial interface. It works with Dash. But I need to interface ten V4 meters to a SCADA system directly and want to work with the 255 bytes HEX datastream that a request generates.
When I use Putty for a Telnet session for testing, I can see the request going out with the Hex Inspector but no data is returned.
What baffles me is that all settings in the iSerial device are apparently correct because Dash works but it won't work for the return when I use Telnet.

Any idea what I am doing wrong? I read everything that I found in the forum that seems relevant. Learned a couple of things too.

Ed

Hey there Ed,

Yes that does sound like a challenge! (the iSerial can be quite a doozie sometimes)

First I would use a separate sniffer hardware component. I would use one of our USB converters and software like CoolTerm or Advanced Serial Port Monitor to actually sniff what the iSerial is requesting. This would be like a 3rd party device that is just viewing the traffic on the RS485 bus. Then I would then read your Omnimeter Pulse v.4 with the EKM Dash via the iSerial. I would compare the results of your Putty request vs the EKM Dash request using CoolTerm.

Can you send me the Hex you are sending and receiving (if any). Also screenshots are always useful.

Here is more about our RS485 serial protocol, with code examples:
http://documents.ekmmetering.com/api-do ... unications

Hi Jameson,
Using the iSerial and Dash, the Hex Inspector shows this string:
2F 3F 30 30 30 33 30 30 30 30 34 30 35 30 30 30 21 0D 0A
after which the response comes. Exactly like described in the API and other threads on this forum.
But when I use this string of bytes with Telnet there is no response coming. I used spaces and \x as separators. No difference.
Saturday morning I already had planned with a friend who is an IT guy to use wireshark on the TCP part of the connection. I will look into your suggestions to sniff the RS485 part as well.

Aside from the iSerial I also tried an USB to RS485 converter. A brandless one from China. I read in one of your comments that the converter from EKM has a superior chip inside which proves to be much more reliable. I ordered one this morning. It will take a while to get here where I live.

I also had two laptops linked. One Macbook with TCP going into the iSerial box. Then the iSerialbox via RS485 and my USB-to-RS485 converter to the second (Windows7) laptop. Results: communication works one way. From the USB device to the iSerial. The reverse route doesn't work. Strange don't you think? Or does this give you a clue? For now I believe the USB converter is at fault for this particular problem which is different than the problem when using the iSerial on the V4.

I will let you know what I find tomorrow.
Thxs,
Ed

Hi Ed,

Yes, I would steer clear of 3rd party USB converters (not that I want to sell more USB converters, just that 3rd party USB converters generate way more headaches than they are worth). We actually dont really help people with 3rd party USB converters as we have wasted plenty of time on them already, only to discover they are built wrong or have the wrong biasing resistor values. Even high cost "good" ones

Yes, your request string with Dash looks correct: 2F 3F 30 30 30 33 30 30 30 30 34 30 35 30 30 30 21 0D 0A

Yes, you will want to verify that the meter is not responding over RS485 vs Telnet not realizing there is data available on the RS485 bus. This is what the sniffer is for. I think until you have a good reliable sniffer that gives you accurate data about the bus, you will be shooting in the dark.