LKM254

Electricity Meter Protocol to Modbus Protocol Gateway with MQTT, 2 x 10/100Base-T(X) Ports, 1 x RS232 and 1 x RS485 Serial Ports

Ethernet Standards 
IEEE 802.3 for 10Base-T
IEEE 802.3u for 100Base-T(X)
IEEE 802.3x Flow Control
Mac Table 
1K MAC address entry
Processing 
Store-and-Forward
Memory 
448K bits packet buffer memory

NTP Server
"NTP Server IP or URL", default pool.ntp.org
After start-up the unit asks the NTP server every 10 seconds until it gets the time, then it keeps the time itself. The time is used for the "Time" field of MQTT messages.
No battery for the clock: after a power cut set the time again, from an NTP server or with "Set Device Time".

Meter Rows
Up to 32 meter rows; the enabled rows are read one after the other
Protocols
IEC 62056-21 (Mode C), DLMS/COSEM, DLMS/COSEM with IEC 62056-21 opening
Meter Interface
RS232 or RS485, set for each meter row (Serial Electricity Meter to Modbus TCP Gateway (and MQTT Publisher)); or meters on the network, IP address and TCP port for each row (TCP/IP Electricity Meter to Modbus RTU Gateway (and MQTT Publisher))
Start Baud Rate
300, 600, 1200, 2400, 4800, 9600, 19200, 38400, 57600 or 115200 for each meter; the unit changes to the baud rate offered by the meter
IEC 62056-21 Settings
IEC address, reading table code (0 to 9), init string (sent 0 to 4 times to wake up the meter), IEC meter line control (7_EVEN_1, 8_NONE_1, 8_EVEN_1)
DLMS/COSEM Settings
meter type, DLMS address, address size (1, 2 or 4 bytes), client type (Management, DataCollection, Electricity, End Customer, Public, ManufacturerSpecific_32), OBIS reference (short names or long names), authentication (Low Security with password, or No Security)
Query Interval
1 to 65535 s for each meter (shortest time between two readings; the real interval can be longer when many meters or long read-out lists are configured)
Time Out
1 to 30 s for each meter
OBIS Codes
up to 48 OBIS codes for each meter profile (IEC 62056-21, Landis+Gyr DLMS, Actaris/Itron, Iskra DLMS, Cewe DLMS, Generic DLMS), set from the web interface

Function Code
03 Read Holding Registers only
Register Size
every value is 32 bits = 2 registers; 48 values per meter row (OBIS index 0 to 47)
Address Rule
address = (meter row - 1) x 256 + 2 x OBIS index (row 1 starts at 0, row 2 at 256, row 3 at 512 ...)
Request
an even number of registers, 2 to 124; each meter row needs its own request
Unit ID / Slave Address
Gateway Modbus Address, 1 to 247 (factory 1)
Byte Order
big-endian inside each register; word order set by "Modbus Word (Register) Swap"
Modbus TCP
port 502 (factory); 1 to 10 masters at the same time (factory 2)
Modbus RTU
RS232 and / or RS485; baud rate 300 to 460800 (factory RS485, 115200, 8_NONE_1); in the function TCP/IP Electricity Meter to Modbus RTU Gateway (and MQTT Publisher)
Exception Responses
none - a request that cannot be served gets no answer

MQTT Publisher
in both device functions, at the same time as Modbus; one message per meter row after a successful reading
Connection
broker IP or URL and port, client ID, user name and password, publish topic and subscribe topic; MQTT 3.1.1 over plain TCP (no TLS encryption), QoS 0
Data Send Interval
"Minimum Send Interval for a Parsed Data (in seconds)", 0 to 65535 s, factory 60 s - the shortest time between two messages of the same meter row
Data Format
OBIS VALUES AS OBJECTS (one JSON object per meter row, OBIS codes and values as text) or OBIS VALUES AS MODBUS FRAME (one hex string: the data part of a Modbus answer with all 48 values of the row)
Time
with the time from NTP every message carries the time as UTC Unix seconds
Broker not reachable
the gateway tries again at most once every 5 seconds and does not restart because of MQTT; meter reading, Modbus and the web pages keep working

Device Status
overview cards for the meters, Modbus, and MQTT with a green, amber, red or grey dot; communication counters
Gateway Status
the result of the last readings and the value stored for every OBIS code, for the last read meter or a selected meter row
Meter Reading Status
the last 210 lines of the meter communication - the data received from IEC meters and the messages of the unit about the readings; the OBIS codes are typed as they appear in the read-out list of the meter

Console Port
USB Type C or Micro USB connection for LOG in 115200 baud
10/100T(X) RJ45 Ports
Ethernet Connection on 2 ports
Serial Ports
5 pin terminal block: RS232 Tx, Rx and GND; RS485 A, B and GND
Reset Buttons
Reset to Factory Settings Buttons

Power Indicator
Power LED
10/100T(X) Indicators

Activity LEDs:
ETH1, ETH2 and Activity of device itself (Marked as device series name, such as CKL/TLM/HUR/LKM)
System Indicators
Status LED,
Tx and Rx of data LEDs and Server LED
Server LED: ON when the device function is Serial IEC Meter to Modbus TCP Gateway, OFF when it is TCP/IP IEC Meter to Modbus RTU Gateway.
Console Indicators
Tx and Rx of data LEDs

Input Range
100 - 240 V AC, 50 Hz to 60 Hz (120 - 370 V DC)
Isolation
> 4200 Vrms, 5 mA, 1 min; insulation class II

Enclosure
Metal, IP40
Dimensions
43 x 95 x 124 mm (w x d x h)
Weight
about 400 g
Storage Temperature
-40 to 85 C
Operating Temperature
-25 to 70 C
Operating Humidity
10 to 95 %, non-condensing
Mounting
DIN rail