DTM-3200 – OEM Ethernet TSoIP Converter
User Manual
19
4.
Device Configuration and Monitoring
4.1
Control interfaces
The DTM-3200 can be configured and monitored using I
2
C, RS-232 (DCE), RS-485 or RS-422. DIP
switch #3 selects between RS-232 and RS-422 or RS-485. It is not required to select between I
2
C
and RS-XXX: The DTM-3200 will automatically use the interface on which it detects activity.
All control interfaces use the same command and response protocol that is described below.
4.2
Command protocol
Commands and responses are wrapped into a frame structure that contains address, category,
setting, read/write, index (optional) and data (optional). The DTM-3200 accepts uppercase and
lowercase characters, but will always respond in uppercase.
4.2.1
Command protocol on RS-232 / RS-422 / RS-485
Field
Format
Description
Start
ASCII character
STX (0x02)
ASCII “start of text” character
Address
2 hex digits
2
8-bit address, with the 6 MSBs fixed to 0x40 and the 2 LSBs
configurable using DIP switches 1 and 2
Category
2 hex digits
Selects a “category” of settings
Setting
2 hex digits
Selects a setting within the selected category
Read/Write ASCII character
‘R’ or ‘W’
‘R’ for read and ‘W’ for write
Index
4 hex digits
(Optional) Provides an extra index parameter, e.g. to
indicate the channel number
3
Data
n hex digits / n
ASCII
characters
4
The data written or read. The data length is variable for
each setting. In case of a write operation, the data is a
(negative) acknowledgement
Checksum 2 hex digits
This is the least significant byte of the two’s complement
5
sum of all characters in the message, excluding the STX and
ETX characters and the checksum itself
End
ASCII character
ETX (0x03)
2
Hex digits are the ASCII characters 0…9 and A…F, concatenated to form a single hexadecimal value.
3
The DTM-3200 supports a single channel only, so index is used as a channel number, it’s always 0.
4
Since firmware version 1.4 the firmware update setting uses ASCII characters 128 to 255 for sending the firmware data.
5
Invert all bits and add one.
