User’s Manual 7M
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ERROR DISPLAY ON LCD
If error is detected Error display appears on LCD after each cycle for 5 seconds.
The first two bits are the summary description of CRC errors.
The decimal value of first 3 Bits (0 ...7) is displayed as Error.
The other bits are shown with 2 values:
- Data CRC – shows Parameter CRC details – decimal value (0...3f) of bits 8 to 13
- Code CRC – shows Firmware CRC details – decimal value (0 ...1f) of bits 3 to 7
CALIBRATION AND SETTING PARAMETERS
Calibration parameters can only be changed in production.
They cannot be changed by upgrade or different processes.
Special factory software is used to calibrate the parameters for current, voltage, and phase angle.
If these parameters were tenaciously or accidentally changed, an error type 1 is detected and Error 1 is shown on the LCD.
Calibration parameters are checked every 64 seconds.
The parameters related to energy measurement can only be changed if the MID key is unlocked.
FREEZE COUNTERS
MEANING
Since 7M.38.8.400.xxxx energy meter does not support internaly synchronised real-time clock (RTC) for the purpose of
simultaneous capture of measurements, the freeze function is implemented.
Use is enabled only when the meter is on.
Freeze function enables using 7M.38.8.400.xxxx smart meters for billing or sub-billing purposes and to compare sub-metering
data with main energy meter.
Reading several hundred serially connected counters can last more than 10 minutes.
That is why 7M.38.8.400.xxxx supports command Freeze counters. Its purpose is to freeze data simultaneously on all devices
in the network.
The freeze function operation is also performed in case of device power supply failure or device reset.
SET UP
To perform the freeze function, the energy meters should be connected to the serial communication RS485 and belonging
software which use Modbus registers.
The energy meter 7M.38.8.400.xxxx enables several ways to activate freeze function:
• Freeze status register,
• time to freeze register,
• auto freeze interval register.
TIME TO FREEZE REGISTER (41902)
The purpose of the time to freeze register is to freeze all energy meters simultaneously.
Set the number of time to freeze register (41902), the value of appropriate time (in seconds) before the time of the freeze
and time of the freeze.
After an expired time, the freeze command is executed automatically.
Due to unreliability in communication, it is recommended that the desired time is sent more than ones, to ensure that freeze
is simultaneous on all instruments. The desired time need to be sent in the interval of one minute.
For example, if you want that freeze function is executed at 10 am, run the command seven times, starting 7 s before 10 am
and repeat it with a one second interval (see the picture below).
All instruments that received one of the commands will freeze at the same time.
This is the advantage of the described register, so it is recommended to use it.
It is also possible to individually enter the appropriate time in register 41902 of each instrument.
