GE 345 Communications Manual page 32

ETHERNET INTERFACE
1–28
Field Name
Slave Address
Function
Byte Count
Data Hi (Register 40172)
Data Lo (Register 40172)
Data Hi (Register 40173)
Data Lo (Register 40173)
Data Hi (Register 40174)
Data Lo (Register 40174)
Data Hi (Register 40175)
Data Lo (Register 40175)
The contents of register 40172 are shown as the two byte values of 00 FE hex, or254
decimal. The contents of registers 40173 to 40175 are 00 04, 00 00 and 00 00 hex, or4, 0
and 0 decimal.
04H Read Input Registers
Reads the binary contents of input registers (3X references) in the slave.
Query:
The query message specifies the starting register and quantity of registers to be read.
Registers are addressed starting at zero: registers 1 to 16 are addressed as 0 to 15.
Here is an example of a request to read register 30305 from slave device 254:
Field Name
Slave Address
Function
Starting Address Hi
Starting Address Lo
No. of Points Hi
No. of Points Lo
Response:
The register data in the response message are packed as two bytes per register, with the
binary contents right justified within each byte. For each register, the first byte contains the
high order bits and the second contains the low order bits.
Field Name
Slave Address
Function
Byte Count
Data Hi (Register 30305)
Data Lo (Register 30305)
05H Force Single Coil
Forces a single coil (0X reference) to either ON or OFF.
The query message specifies the coil reference to be forced. Coils are addressed starting at
zero: coil 1 is addressed as 0.
The reguested ON/OFF state is specified by a constant in the query data field.
CHAPTER 1: COMMUNICATIONS GUIDE
Hex
FE
03
08
00
FE
00
04
00
00
00
00
Hex
FE
04
01
30
00
01
Hex
FE
04
02
80
80
345 TRANSFORMER PROTECTION SYSTEM – COMMUNICATIONS GUIDE