Entellipro Es Function Code; Function Code 03H - GE EntelliPro ES Series Installation And Instruction Manual

4.1.10 EntelliPro ES Function Code

The following sections describe the Modbus function code supported by the EntelliPro ES.

4.1.10.1 Function code 03H

For the EntelliPro ES implementation of Modbus, this function code can be used to read any setpoints ("holding
registers"). Holding registers are 16 bit (two byte) values transmitted high order byte first . Thus all EntelliPro ES Setpoints
are sent as two bytes. The maximum number of registers that can be read in one transmission is 125.
The slave response to this function code is the slave address, function code, a count of the number of data bytes to
follow, the data itself and the CRC. Each data item is sent as a two byte number with the high order byte sent first .
For example, consider a request for slave II to respond with 3 registers starting at address 006B. For this example the
register data in these addresses is as follows:
The master/slave packets have the following format:
MASTER TRANSMISSION
SLAVE ADDRESS
FUNCTION CODE
DATA STARTING ADDRESS
NUMBER OF SETPOINT
CRC
SLAVE RESPONSE
SLAVE ADDRESS
FUNCTION CODE
BYTE COUNT
DATA 1 (see definition above)
DATA 2 (see definition above)
DATA 3 (see definition above)
CRC
Table 4-2: Master/Slave Packet Format For Function Code 03H
EP OS MOTOR MANAGEMENT SYSTEM – INSTRUCTION MANUAL
Address Data
0002 0001
0003 0000
0004 0012
BYTES
1
1
2
2
2
BYTES
1
1
1
2
2
2
2
CHAPTER 4: COMMUNICATION
EXAMPLE DESCRIPTION
message for slave 17
11
03 read registers
00 6B data starting at 006B
00 03 3 registers = 6 bytes total
78 87 CRC error code
EXAMPLE DESCRIPTION
11 message from slave 17
03 read registers
06 3 registers = 6 bytes
02 2B value in address 006B
00 00 value in address 006C
00 64 value in address 006D
54 83 CRC error code
4.8