Allen-Bradley 825-P, User Manual

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Rockwell Automation Publication 825-UM004D-EN-P - November 2012 145
Modbus RTU Communications Chapter 10
To discard settings, either write a 0x0001 to the Discard Settings register of the
Control I/O region, write a 0x0001 to the Drop Access Level register of the
Control I/O region or wait fifteen minutes since last write for access level
timeout.
Modbus Serialized Events
Recording Register
Operation
To obtain Serialized Events Recording (SER) records using the Modbus
register map perform the following steps.
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.
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.
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…20.
Modbus Load Profile
Register Operation
To read load profile data from the 825-P using the Modbus map, perform the
following steps.
1.
Read the Load Profile 1 Name to Load Profile 12 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.
2.
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.
Up to 100 records are available on or after the selected date and time.
Channels that are not profiling data returns a reserved value when read
(see Table 84).
Table 84 - Modbus Conversion
Conversion Description Reserved Value
INT Value ranges = –32767…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