21
5
Min. request period
(Controller to PSU/CHG): 50mSec。
Max. response time
(PSU/CHG to Controller): 12.5mSec。
Min. packet margin time
(Controller to PSU/CHG): 12.5mSec。
5 4 1.2
. .
Communication nterface
I
(Controller to PSU/CHG)
Packet Margin time
（
）
Controller to PSU/CHG
PSU TX
PSU RX
(form Controlle )
r
(
C
)
PSU/ HG to Controller
Request period
Response time
5.4.1.3
Modbus rame ncapsulation
F
E
1 byte
Additional address
1 byte
N bytes
2 bytes
Function code
Data
Error check
Additional address (1byte): defines PSU slave ID
Function code (1byte): The function code is used to tell the slave what
kind of action to perform.
Data (N bytes): For data exchange, contents and data length are
dependent on different function codes.
Error Check (2bytes): utilizes CRC-16.
M
us RTU
odb
consists of Additional Address, Function Code, Date
and Error Check.
5.4.1.4 Additional Address
Definition
Additional address is the slave ID of the device. Each DRS unit
should have their unique and own device address to communicate
over the bus. Slave ID is set by CN12 (A0~A1)
The device address is set as follows:
22
5
5.4.1.5 Function Code
Description
The main purpose of the function codes is to tell the slave what kind
of action to perform. For example, function code 03 will query the
slave to read holding registers and respond the master server with
their contents
.
Function Code of DRS as follow：
Read Holding Register
Read Input Register
Preset Single Register
0x03
0x04
0x06
Parameter register read
Analog register reads
Write to single staging area
Function Code
Description
Quantity of (Input) Registers
FC=03/04
Starting Address
2 Bytes
2 Bytes
FC=06
Register Addressr
Register Value
2 Bytes
2 Bytes
Data field provides additional information by the slave to complete
the action specified by the function code in a request. The data field
typically includes register addresses, count values, and written data.
There are two forms according to the function codes.
5.4.1.6 Data
field and command lists
0
x00
Note:
Broadcast is only for command write but not read.
Broadcast
0
x8X
Slave ID
X means device address
Description
Between A0/A1 and GND
（Single）
Open
Short
0
1
2
3
1
0
Device No.
Device address
A1
0
0
1
1
Iogic
A0
0
1
0
1