Справочник Пользователя для Schneider Electric EM3555

22

© 2011 Schneider Electric All Rights Reserved.

The EM3555 includes a data logging feature that records 10 meter parameters, 

each in its own buffer. 

Use register 150 to set the data logging time subinterval. Writing to the storage 

buffer is triggered by the subinterval timer. The default subinterval is 15 minutes 

(at a 15 minute interval setting, the buffers hold 60 days of data). An external 

timer can be used over Modbus by setting this register to 0.

Use register 159 to turn on data logging and select either Single Shot or 

Continuous mode. The default settings are data logging on and set to 

Continuous mode. In Single Shot mode, the meter records data until the buffer 

is full. When the buffer is full, the meter stops recording new readings. Data 

for this time period is kept, but newer energy information is lost. In Continuous 

mode, the meter continues to record energy data as long as the meter is 

operating. The buffer can only hold 5760 entries at one time, however, so when 

the number of records exceeds 5760, the oldest entry is deleted to make room 

for the newest.

Registers 169-178 contain the pointers to 10 data storage buffers. Each buffer 

is user-configurable with the Modbus address of the 16-bit data output to be 

stored. Measurement variables with 32-bit data, such as floating point data or 

32-bit integer energy accumulators, require two buffers. However, the lower 16 

bits of an integer energy accumulator can be stored in a single buffer (optional).

When the EM3555 is first installed, the buffers contain QNAN data, with a value 

of 0x8000. This data is considered invalid. If the buffer is reset at any point, all 

entries in the buffers are overwritten with this 0x8000 value, indicating that it is 

invalid. All invalid data is overwritten as the meter fills the buffer with new data 

entries. 

Use register 158 to choose which buffer to read. When this register value is set 

to 0, the meter is in data logging mode. Changing this value from 0 (to 1 through 

10) switches the meter to reading mode and selects a buffer to read. Data from 

the selected buffer appears in registers 8000 to 13760.  

If the demand sub-interval timeout occurs while the user is reading a page 

(register 158 ≠ 0), the log data will be held in RAM until the next demand 

subinterval. At that time, both the saved data from the previous cycle and 

the new data will be written to the log, whether the page register has been 

set back to 0 or not. Error bits in the Log Status Register (160) track these 

conditions. Subsequent log writes will proceed normally. Provided the log read 

is concluded in less time than the demand sub-interval, this mechanism handles 

the occasional collision and prevents the user from reading data as the buffer is 

being updated.

The Log Status Register has additional error flag bits that indicate whether 

logging has been reset or interrupted (power cycle, etc.) during the previous 

demand sub-interval, and whether the Real Time Clock has been changed 

(re-initialized to default date/time due to a power-cycle or modified via Modbus 

commands).