Exception And Error Responses; Request Response Sequence - GE 345 Communications Manual

CHAPTER 1: COMMUNICATIONS GUIDE
Exception and error
responses
Request response
sequence
345 TRANSFORMER PROTECTION SYSTEM – COMMUNICATIONS GUIDE
Response:
Field Name
Slave Address
Function
Byte Count
Data Hi
Data Lo
43H Write Settings Group
Not a standard function
This function is used to write settings in a specific settings group.
Example: (In the example there is a write setting procedure in the Group 1 (00) , setting
address 0x09C1 and 2 bytes of data with value 0x0001.)
Field Name
Slave Address
Function
Group Activation
Starting Address Hi
Starting Address Lo
No. of Registers Hi
No. of Registers Lo
Byte Count 04
Data Hi
Data Lo
Response:
Field Name
Slave Address
Function
Starting Address Hi
Starting Address Lo
No. of Registers Hi
No. of Registers Lo
One data frame of an asynchronous transmission to or from a 345 typically consists of 1
start bit, 8 data bits, and 1 stop bit. This produces a 10 bit data frame. This is important for
transmission through modems at high bit rates.
Modbus protocol can be implemented at any standard communication speed. The
SR350supports operation at 9600, 19200, 38400, 57600, and 115200 baud.
A complete request/response sequence consists of the following bytes (transmitted as
separate data frames):
Master Request Transmission:
SLAVE ADDRESS: 1 byte
FUNCTION CODE: 1 byte
DATA: variable number of bytes depending on FUNCTION CODE
ETHERNET INTERFACE
Hex
FE
42
02
00
00
Hex
FE
43
00
09
C1
00
01
02
00
01
Hex
FE
43
09
C1
00
01
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