DekTec DTM-3237 DVB-S2 Receiver - Manual (Page 15)

DTM-3237 – OEM DVB-S2 Receiver with DVB-ASI Output
User Manual
15
The DTM-3237’s LVTTL serial control port is designed to interface directly with a microprocessor
system. The serial control port uses the same protocol as RS-232, but the I/O voltages are entirely
different. This LVTTL serial control interface is not compatible with a RS-232 port, e.g. a PC’s COM-
port, due to its different voltage.
Do not connect the LVTTL serial control port to a PC’s COM-port
Connecting the LVTTL serial control port of the DTM-3237 to a PC’s COM port may cause
permanent damage to the DTM-3237.
RS-232 DTM-3237 LVTTL serial control port
Digital ‘0’ +3V … +15V 0V
Digital ‘1’ -3V … -15V +3.3V
Figure 2 below shows the structure of a command written through the serial interface. If the command
is a read-command, the data may be omitted. Note that some settings require an index.
Figure 2. Command on an USB and LVTTL serial control port serial control interface
All commands successfully sent to the DTM-3237 are answered with a copy of the command including
the data bytes.
When an incorrect checksum or an invalid hex value is detected, the DTM-3237 will not return an
answer. When protocol errors are detected, e.g. a combination of a valid category with an invalid
setting, the R/W byte of the reply is replaced with the ASCII character ‘E’ and the data is removed from
the message.
Please refer to Appendix D for a communication example.