RS-485 communication fails

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tsprad
Posts: 2
Joined: Wed Aug 29, 2018 12:02 pm
Location: Farmers Branch Texas

RS-485 communication fails

Post by tsprad » Mon Sep 10, 2018 2:29 pm

Trying to establish communication with Omnimeter V4 using Blink and EKM Dash on Debian Stretch, but it just keeps scrolling "Bad Meter Response" in red on the left side of the display. Here's what Hex Inspector shows me:


Send
2F 3F 30 30 30 33 35 30 30 30 33 32 32 39 30 30
21 0D 0A
[Request Data A from meter# 350003229]

Receive
02 10 24 1D 30 30 30 33 35 30 30 30 33 32 32 39
30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30
30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30
30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30
30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30
30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30
30 30 30 30 30 30 30 30 31 31 38 34 30 30 30 30
30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30
30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30
30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 4C
30 39 39 43 30 30 30 43 30 30 30 30 30 30 30 30
30 30 30 30 30 30 30 30 30 30 30 30 30 30 30 30
30 30 30 30 30 30 30 36 30 30 32 30 30 30 30 30
30 30 34 30 30 30 30 30 30 30 30 30 30 30 30 30
30 30 30 30 31 31 32 30 30 31 38 30 39 31 31 30
33 30 35 31 30 35 36 30 30 21 0D 0A 03 4D 23
[Data A, Model: 1024, Firmware: 1D, Meter_Address: 350003229, kWh_Tot: 0.00, Reactive_Energy_Tot: 0.00, Rev_kWh_Tot: 0.00, kWh_Ln_1: 0.00, kWh_Ln_2: 0.00, kWh_Ln_3: 0.00, Rev_kWh_Ln_1: 0.00, Rev_kWh_Ln_2: 0.00, Rev_kWh_Ln_3: 0.00, Resettable_kWh_Tot: 0.00, Resettable_Rev_kWh_Tot: 0.00, RMS_Volts_Ln_1: 118.4, RMS_Volts_Ln_2: 0.0, RMS_Volts_Ln_3: 0.0, Amps_Ln_1: 0.0, Amps_Ln_2: 0.0, Amps_Ln_3: 0.0, RMS_Watts_Ln_1: 0, RMS_Watts_Ln_2: 0, RMS_Watts_Ln_3: 0, RMS_Watts_Tot: 0, Power_Factor_Ln_1: L099, Power_Factor_Ln_2: C000, Power_Factor_Ln_3: C000, Reactive_Pwr_Ln_1: 0, Reactive_Pwr_Ln_2: 0, Reactive_Pwr_Ln_3: 0, Reactive_Pwr_Tot: 0, Line_Freq: 60.02, Pulse_Cnt_1: 4, Pulse_Cnt_2: 0, Pulse_Cnt_3: 0, State_Inputs: 0, State_Watts_Dir: 1, State_Out: 1, kWh_Scale: 2, Meter_Time: 18091103051056]

Send
01 42 30 03 75
[Stop communication with meter# 350003229]

This all looks reasonable to me, but I haven't yet tried to check the checksum. Any hints what to look at next?

I have the Omnimeter V4, the Pulse, and the Blink all connected together using the green pairs of short (20 inches) lengths of Cat 5 with a third piece of Cat5 for the oscilloscope probes. I was seeing about 5 volts of 60 Hz common-mode noise on the RS-485 with the Blink disconnected, but the Blink suppresses that, and it shouldn't be a problem anyway since it's common mode (both A and B lines have the same noise except when there is data on the line.

Jameson
Posts: 749
Joined: Fri Nov 04, 2011 7:42 pm
Location: Santa Cruz, CA
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Re: RS-485 communication fails

Post by Jameson » Thu Sep 13, 2018 7:22 am

Your data all looks very good. I would imagine that this is a problem that we saw with one of our customers already. They were running Dash on Fedora Linux. It turned out that there was an issue with how the public version of Dash was calculating the checksum in Fedora.

We have since fixed this in the dev version of the Dash. If you send us an email to support@ekmmetering.com we can send you the dev version to see if it will work for you. Would you like to try it out?
Jameson
EKM METERING
http://www.ekmmetering.com
831.425.7371

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