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CHAPTER 1: COMMUNICATIONS GUIDE
345 TRANSFORMER PROTECTION SYSTEM – COMMUNICATIONS GUIDE
This is a function used to quickly read the status of a selected device. A short message
length allows for rapid reading of status. The status byte returned will have individual bits
set to 1 or 0 depending on the status of the slave device. For this example, consider the
following 350 general status byte:
The master/slave packets have the following format:
Mask
0x01
0x02
0x04
0x08
0x10
0x20
0x40
0x80
Query:
Field Name
Slave Address
Function
Response:
Field Name
Slave Address
Function
Device Status (see definition above)
08H Diagnostics
Just respond, no action required for now.
Serves as a loopback test.
Outgoing message for this function is the same as input one.
16 (10 Hex) Preset Multiple Registers
Presets values into a sequence of holding registers (4X references.
Query:
The query message specifies the register references to be preset. Registers are addressed
starting at zero: register 1 is addressed as 0.
The requested preset values are specified in the query data field. Data is packed as two
bytes per register.
Here is an example of a request to preset two registers starting at 43851 to 00 01 and 00
00 hex, in slave device 254:
Function
Alarm
Trip
Self Test Fault
Breaker Connected
52a Status
52b Status
Maintenance
In Service
Hex
FE
07
Hex
FE
07
2C
ETHERNET INTERFACE
1–33
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