Details about Function Parameters
143
0
～
15 16
～
31 32
～
47 48
～
59
﹠
The SB200 inverter series support the Modbus protocol in RTU mode (Remote Terminal Unit).
Supported functions include Function 3 (capable of reading multiple parameters; the largest number of
words is 50), Function 16 (capable of writing multiple parameters; the largest number of words is 10),
Function 22 (mask writing) and Function 8 (loop test). Functions 16 and 12 support broadcasting. RTU
frames begin and end with a time interval of at least 3.5 characters (but the interval is 2ms for such
baud rates as 19200bit/s and 38400bit/s). A typical RTU frame has the following format:
Slave Address (1
byte)
Modbus Function Number
(1 byte)
Date (Multiple
bytes)
CRC16 (2
bytes)
Data Format and Sending Sequence of a Byte: 1 start bit, 8 data bits, 1 parity check bit (or no such bit)
and 1 or 2 stop bits. Range of Slave Address: 1—247. If the message address is 0, it’s a broadcast
message. Cyclic Redundancy Check (CRC): CRC16 (lower bytes before higher bytes).
Function 3: Multi-reading. The range of number of words read is 1—50. See the following
example for the format of a message:
Example: Reading the Primary Status Word, Working Frequency and Arithmetic Unit 1 Output of Slave
#1 (the address is the first 3 words of 3210H):
Master Request:
Slave Response:
Slave Address
01H
Modbus Function
mber
03H
Number of Bytes
urned
06H
Slave Address
01H
Higher Byte with
0H
44H
Modbus Function
Number
03H
Lower Byte with 3210H
37H
Start Address (Higher
byte)
32H
Higher Byte with
1H
13H
Start Address (Lower
byte)
10H
Lower Byte with 3211H
88H
Number of Words Read
(Higher byte)
00H
Higher Byte with
2H
00H
Number of Words Read
(Lower byte)
03H
Lower Byte with 3212H
00H
CRC (Lower byte)
0AH
CRC (Lower byte)
5FH
CRC (Lower byte)
B6H
CRC (Higher byte)
5BH
Write Once: 06H
Summary of Contents for SB200 Series
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