AccuEnergy AcuRev 2000, User Manual

Page: 123 / 270

115
Frame Format
Address Function Data Check
8-Bits 8-Bits N×8-Bits 16-Bits
Table 5-1 Data Frame Format
Address Field
The address field is at the start of the frame. It is composed of 1 byte (8 bits), its decimal
value range is 0-247.
A master addresses a slave by placing the slave address in the address field of the
message. When the slave sends its response, it places its own address in this address field
of the response to let the master know which slave is responding.
Function Field
When a message is sent from a master to a slave device the function code field tells the
slave what kind of action to perform.
Code Meaning Action
01 Read DO status Obtain Digital (Relay) Output current status (ON/OFF)
02 Read DI status Obtain Digital Input current status (ON/OFF)
03 Read Data Obtain current binary value from one or more registers
05 Control DO Control Digital (Relay) Output(ON/OFF)
16
Preset multiple
registers
Place specifc value into a series of consecutive multiple-registers
Table 5-2 Function Code