Function Code 10H; Error Responses - GE 345 Communications Manual

CHAPTER 1: COMMUNICATIONS GUIDE

Function Code 10H

Error Responses

345 TRANSFORMER PROTECTION SYSTEM – COMMUNICATIONS GUIDE
Modbus Implementation: Preset Multiple Registers
345 Implementation: Store Multiple Setpoints
This function code allows multiple Setpoints to be stored into the 345 memory. Modbus
"registers" are 16-bit (two byte) values transmitted high order byte first. Thus all 345
setpoints are sent as two bytes. The maximum number of Setpoints that can be stored in
one transmission is dependent on the slave device. Modbus allows up to a maximum of 60
holding registers to be stored. The 345 response to this function code is to echo the slave
address, function code, starting address, the number of Setpoints stored, and the CRC.
For example, consider a request for slave 17 to store the value 00 02 to setpoint address 04
5C and the value 01 F4 to setpoint address 04 5D. After the transmission in this example is
complete, 345 slave 17 will have the following setpoints information stored:
Address
04 5C
04 5D
The master/slave packets have the following format:
Table 40: MASTER/SLAVE PACKET FORMAT FOR FUNCTION CODE 10H
MASTER TRANSMISSION
SLAVE ADDRESS
FUNCTION CODE
DATA STARTING ADDRESS
NUMBER OF SETPOINTS
BYTE COUNT
DATA 1
DATA 2
CRC
SLAVE RESPONSE
SLAVE ADDRESS
FUNCTION CODE
DATA STARTING ADDRESS
NUMBER OF SETPOINTS
CRC
When a 345 detects an error other than a CRC error, a response will be sent to the master.
The MSBit of the FUNCTION CODE byte will be set to 1 (i.e. the function code sent from the
slave will be equal to the function code sent from the master plus 128). The following byte
will be an exception code indicating the type of error that occurred.
Transmissions received from the master with CRC errors will be ignored by the 345.
The slave response to an error (other than CRC error) will be:
SLAVE ADDRESS: 1 byte
Data
00 02
01 F4
BYTES EXAMPLE
1 11
1 10
2 04 5C
2 00 02
1 04
2 00 02
2 01 F4
2 31 11
BYTES EXAMPLE
1 11
1 10
2 04 5C
2 00 02
2 82 7A
MODBUS FUNCTIONS
DESCRIPTION
message for slave 17
store setpoints
setpoint address 04
5C
2 setpoints = 4 bytes
total
4 bytes of data
data for setpoint
address 04 5C
data for setpoint
address 04 5D
CRC error code
DESCRIPTION
message from slave
17
store setpoints
setpoint address 04
5C
2 setpoints
CRC error code
1–175