F.10
SEL-734 Meter Instruction Manual Date Code 20090730
Modbus RTU Communications Protocol
Modbus RTU Communications Protocol
Modbus Sequence
Event Recorder
Register Operation
To obtain Sequence Event Recorder (SER) records by using the Modbus
register map, perform the following steps.
Step 1. Write the date and time for the first desired record to the Start
Record Time/Date registers of the SER region of the map.
Step 2. Read the Number of Records Available register to determine
how many SER records are available on or after the selected
date and time.
Ten records are available for reading from the SER region of
the map.
Step 3. Write to the Selected Starting Record register to select
additional records from the number available.
For example, if the number of records available is 25, write 11
to the selected starting record to read records 11 to 20.
Modbus Load Profile
Register Operation
To read load profile data from the SEL-734 by using the Modbus map,
perform the following steps.
Step 1. If reading an SEL-734P that supports up to 12 independent
LDP recorders, please refer to Note 1 at the end of Table F.23.
Step 2. Read the Load Profile 1 Name to Load Profile 16 Name
registers from the Product Information region of the map.
These names are returned as a NULL terminated ASCII string
and provide the human-readable label for the profiled data. If
the load profile channel is unused, then the associated label is
an empty string.
Step 3. Write the date and time for the first desired record to the Start
Record Time/Date registers of the Load Profile region of the
map.
As many as 100 records are available on or after the selected
date and time. Channels that are not profiling data return a
reserved value when read (see Table F.22 ).
Modbus TCP
Modbus TCP is available over Ethernet (Port 1). Determine appropriate
ethernet port settings (i.e., IP, Default Router, and Subnet Mask) for your
network. Send Modbus requests to Port #502. The SEL-734 Ethernet port
supports three simultaneous sessions (see Ethernet on page 10.4).
Table F.22 Modbus Conversion (Sheet 1 of 2)
Conversion Description
Reserved
Value
INT Value ranges from –32767 to 32767 0x8000
INT10 INT with scale factor of 10 (divide by 10 to obtain value) 0x8000
INT100 INT with scale factor of 100 (divide by 100 to obtain value) 0x8000
INT1000 INT with scale factor of 1000 (divide by 1000 to obtain value) 0x8000
UINT Value ranges from 0 to 65535 0x8000
UINT10 UINT with scale factor of 10 (divide by 10 to obtain value) 0x8000
UINT100 UINT with scale factor of 100 (divide by 100 to obtain value) 0x8000
UINT1000 UINT with scale factor of 1000 (divide by 1000 to obtain value) 0x8000
LONG Value ranges from –2147483647 to 2147483647, most significant word in lower address register 0x80000000
Courtesy of NationalSwitchgear.com
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