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Read Energy Totalizer Command
Preamble #
Addr 00 to FF
Dir W
Data not used
Transducer Correct Response:
Period Counter (00 to FF)
KWHr Data (+/-XXXXXX)
KVHr Data (+/-XXXXXX)
Checksum (XX)
<cr>
Transducer Wrong Response: ?
Addr (00 to FF)
<cr>
Description of Totalizer Function
The energy totalizer function is a method by which the total
amount of energy in KwHrs and KVARHrs used over a period of
time can be measured. A data location within the program keeps
a running total of the amount of energy used. This total starts
from zero and begins totalizing the instant power is turned on to
the transducer.
Totalizer data is outputted when the Read Energy Totalizer
Command is sent to the transducer. At this point, the transducer
outputs the amount of energy totaled since the last clear or
restart. A counter called the time period counter, keeps track of
all instances of requested totalizer data. Thus, at turn on, the
period counter is set to zero. After the first read of totalizer data,
the counter is incremented by 1 and reads 1. Future requests for
data increase the period counter by 1. This counter turns back to
zero after 255 counts (FF).
It is important to know that the output data represents the amount
of energy used since the last clear or restart. This method
makes it very useful for total energy used calculations.
A Clear Totalizer Command function is also provided to reset the
totalizer as needed.
The largest period of totalizer data is 1,553.5 Hours with the full
scale voltage and current being input to the device. Longer peri
ods are possible with lower input voltages and currents.
The data output has gain and function factors that must be
included when calculating actual KwHr/KVARHr. The formula is:
Energy = Data Read X Volt Range X Current Range / 3600000
Units are KwHrs and KVARHrs depending on data read.
Please note: Unlike other data read from the transducer, the
energy data is transmitted as the ASCII representation of the
HEX value. Hence, when the data would return as ASCII "FF",
this is equivalent to the decimal value 255.
Checksum data is provided as a verifier of correct data communi
cation. The Checksum data is generated by totaling the sum of
all byte by byte data, in HEX, sent from the transducer after the
Read Energy Totalizer Command is accepted, then taking this
HEX value and performing a logical AND with the value FFH, and
outputting it. The data is an ASCII representation of the HEX
value.
Example: Given a CRD5110, programmed with a Voltage range
of 500VAC RMS, and a Current range of 5 AAC
RMS, and Address 1B. Input Voltage =300 VAC
RMS, Input current = 4 AAC RMS, Power Factor =
1.000 (Pure resistive) and a frequency of 50 Hz.
Energy data has not been requested since turn on of
the part. The command is sent after the part has
been running one hour.
Send #1BW<cr>
Receive >01+0006C0+0000001E<cr>
Time Period = 01H = 1 Decimal
KwHr Data = +0006C0H = 1,728 Decimal
KwHr Actual = 1,728 X 500 X 5 / 3600000 = 1.2 KwHrs
KVARHr Data = +000000H = 0 Decimal
KVARHrs Actual = 0 KVARHrs
Checksum = 1EH
Doing the Check on the Checksum:
3EH+31H+2BH+30H+30H+30H+36H+43H+30H+2BH+30H+30H
+30H+30H+30H+30H = 31EH AND FFH = 1EH
Read Transducer Configuration Command
Preamble $
Addr 00 to FF
Dir 2
Data not used
Transducer Correct Response: !
Addr (00 to FF)
Input Range (Always 00)
Baud Rate Code (See Below)
Data Format (Always 01)
<cr>
Transducer Wrong Response: ?
Addr (00 to FF)
<cr>
Example: Send $0A2<cr>
Receive !0A000601<cr>
In this case, a CRD5110 Multifunction transducer is programmed
with the address 0A. Reading the configuration returns 0A for
the address, 00 for the Input Range (fixed), 06 for 9600 bps
Baud rate, and 01 for no check sum on standard data (Data
Format is fixed).
Baud Rate Codes are as follows:
03 = 1200 bps
04 = 2400 bps
05 = 4800 bps
06 = 9600 bps (Default)
07 = 19200 bps
Programming (continued)
DATA STREAM RS485 DIGITAL TRANSDUCER