Installation Manual

Communications
H-Max HVAC Drives MN04008006E—January 2012 www.eaton.com 109
Example 2
Read the Process Data 42103…42104 with command 4 (Read Input Registers).
Command Master – Slave:
Message frame:
The reply to the Read Input Registers message contains the values of the read registers.
Answer Slave – Master:
Reply frame:
ADDRESS 01 hex Slave address 1 hex (= 1)
FUNCTION 04 hex Function 4 hex (= 4)
DATA Starting address HI 08 hex
Starting address LO 36 hex
No. of registers HI 00 hex Number of registers 0002 hex (= 2)
No. of registers LO 02 hex
ERROR CRC HI 93 hex CRC field 93A5 hex (= 37797)
CHECK CRC LO A5 hex
01 04 08 36 00 02 93 A5
ADDRESS 01 hex Slave address 1 hex (= 1)
FUNCTION 04 hex Function 4 hex (= 4)
DATA Byte count 04 hex Byte count 4 hex (= 4)
Data HI 13 hex Speed reference = 1388 hex (=5000 => 50.00%)
Data LO 88 hex
Data HI 09 hex Output Frequency = 09C4 hex (=2500 =>25.00 Hz)
Data LO C4 hex CRC HI 78 hex
ERROR CRC field 78E9 hex (=30953)
CHECK CRC LO E9 hex
01 04 04 13 88 09 C4 78 E9