AccuEnergy AcuDC 241, Руководство пользователя

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Code Meaning Action
01 Read RO status
Obtain Relay Output current status (ON/OFF)
02 Read DI status
Obtain Digital Input current status (ON/OFF)
03 Read holding register
Obtain current binary value of one or multiple registers
05
Control RO Control Relay Output(ON/OFF)
16
Preset multiple registers
Place specifc binary value into multiple registers
Table 4-2 Function Code
2.4 Data Field
Data field contains the data that terminals need to complete the request and the data that
terminals respond to the request. This data may be a numerical value, address or setting.
For example, Function Code tells the terminal to read one register, Data Field needs to
specify reading from which register and how many registers to read.
2.5 Error Check Field
The field allows the error check by master and slave devices. Due to electrical noise and
other interferences, a group of data may be changed while transmitting from one location
to the other. Error Check ensures master or slave devices do not respond to the distorted
data during the transmission, which enhances the system security and efficiency. Error
Check uses 16-bit Cyclic Redundancy Check (CRC 16).
2.6 CRC Check
Every message includes an error checking field which is based on the Cyclical Redundancy
Check (CRC) method. The CRC field checks the contents of the entire message. It is applied
regardless of any parity check method used for the individual characters of the message.
The CRC field is two bytes long, containing a 16-bit binary value. The CRC value is calculated
by the transmitting device, and is appended to the message.