厦 门 四 信 通 信 科 技 有 限 公 司
Xiamen Four-Faith Communication Technology Co., Ltd.
Add：J1-J2,3rd Floor,No.44,GuanRi Road,SoftWare Park,XiaMen,China
11
Zip Code
：
361008
Tel：+86 592-6300320, +86 592-6300321, +86 592-6300322 Fax：+86 592-5912735 http://
www.four-faith.com www.fourfaith.com
Backup Center DNS Server is used to resolve the Main center and Backup center
correspondingly.
AT command of Main Center DNS server:
AT+DNSSVR=aaa.bbb.ccc.ddd
aaa.bbb.ccc.ddd: The DNS server IP address(must be IP address
）
.
AT command of Backup Center DNS server:
AT+DNSSV2=aaa.bbb.ccc.ddd
aaa.bbb.ccc.ddd: the DNS server IP address
◆
Center 2~5 DNS Server
When the DTU work in Multi Data Service Center method and the centers use
domain name, 2~5 DNS server is used to resolve center 2~5 correspondingly.
AT command of 2~5 DNS Server
AT+DNSSVRn=aaa.bbb.ccc.ddd
n is 1~4 correspond to center 2~5 DNS server.
aaa.bbb.ccc.ddd is the DNS server IP address
3.2.3.2 DTU Settings
◆
DTU WorkMode
According to different application requirements, there are several protocol
workmode to choose.
PROT
：
Heartbeat packet with TCP protocol, Data transmission with TCP protocol,
heartbeat packet and application data transmission are in the same TCP
connection.
TRNS
：
DTU work as a common EDGE MODEM, It can be used in SMS, CSD,
Dial-up applications.
TTRN
：
Heartbeat packet with UDP protocol, Data transmission with TCP protocol
TLNT
：
DTU work as a telnet client
LON
G：
Heartbeat packet with UDP protocol, Data transmission with TCP protocol, It
can transmit at most 8192 bytes data one time through extra application
protocol.
LNGT
：
Heartbeat with UDP protocol, Data transmission with TCP protocol, It can
transmit at most 8192 bytes data one time through extra application protocol.
TUD
P：
Heartbeat with UDP protocol, Data transmission with UDP protocol, Heartbeat
packet and application data are in the same UDP connection.
