Rs232/Rs485 Command; Environment; Sample - Advantech DSD-3000 Series User Manual

3.3

RS232/RS485 Command

3.3.1

Environment

Interface
Baud Rates
Data Bits
Stop Bits
Parity
3.3.2

Sample

STX Address/ID
02 00
General Command Form
 STX
The first character is the standard Start of Text (STX) character 02.
 Address/RS485ID
The second and third characters are the device address. If a device does not
support addressing, the values for these characters should be 00 and 00 to act
as the global address.
 Type
The fourth character is the command type. Four types of commands exist:
– Command
→
– Ack
 Property/Command
The fifth and sixth characters are the property identifier. With the use of two-
byte identifiers, a possible 65,536 different identifiers exist. Although this may
seem excessive, the maximum of 256 one-byte identifiers is insufficient for cer-
tain models.
 Data Length
The seventh character is the number of characters in the parameter data sec-
tion.
 Data
The data parameter section follows the seventh character, and is as many char-
acters long as specified by the seventh character. If the seventh character is 00
(as with the Reset command for example) then the parameter section will have
no characters. The parameter section contains the value of the property.
 ETX
The last character is the standard End of Text (ETX) character 03.
In this example (changing the input source to VGA), the Address characters are both
00, which is the global address for all devices connected to the serial port. The Type
character is 01 to indicate that the transmission is a command.
The Property ID characters indicate a property identifier of 2, which is the value in
this protocol.
RS232, RS485
19200
8
1
No
Type Property/Command
00 01 00
→
01
02
Length Data
02 01 31
19 DSD-3000 Series User Manual
ETX Checksum
03 3A