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RJ-MODEM 脚位定义：
1 –RI O RING (Active Low). Incoming ring signal from phone.
Ring Indicate. –RI output ON (low) indicates the presence of an ON segment of a
ring signal on the telephone line. The modem will not go off-hook when –RI is active;
the modem waits for –RI to go inactive before going off-hook.
2 –DCD O Data Carrier Detect (Active Low). –DCD output is ON (low) when a data
connection is established and the module is ready to send/receive data.
3 –DTR I Data Terminal Ready (Active Low). The –DTR input is turned ON (low) when the
DTE is ready to communicate. –DTR ON prepares the modem to be connected, and,
once connected, maintains the connection. –DTR OFF places the modem in the
disconnect state under control of the &Dn and &Qn commands.
6 –CTS O Clear to Send (Active Low). –CTS is controlled by the module to indicate whether or
not the module is ready to transmit data. –CTS ON indicates to the DTE that signals
on TXD will be transmitted. –CTS OFF indicates to the DTE that it should not transfer
data on TXD.
7 –RTS I Request to Sent (Active Low). –RTS signal is used for hardware flow control. –RTS
input ON (low) indicates that the DTE is ready to send data to the modem. In the
command state, the modem ignores –RTS.
8 TXCLK O Transmit Data Sync Clock. TX synchronous data clock for sync data mode.
9–TXD I Transmitted Data. The DTE uses the –TXD line to send data to the module for
transmission or to transmit commands to the module. The DTE should hold this
circuit in the mark state when no data is being transmitted or during between intervals
between characters.
10 –RXD O Received Data. The module uses the RXD line to send data to the DTE and to send
module responses to the DTE. In command mode, –RXD data presents the module
responses to the DTE. Module responses take priority over incoming data when the
two signals are in competition for –RXD. When no data is transmitted, the signal is
held in mark condition.
13 SPKR Speaker. Call Progress signaling on MT5656RJ is a square wave output that can be
optionally connected to a low-cost single-ended speaker; e.g., a sounducer or an
analog speaker circuit.
14 RXCLK I Receive Data Sync Clock. RX synchronous data clock for sync data mode.
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如附图中，是系统的示意图，有“A型”，和“B型”。
A型：
目前连接已通过，工作正常。
连接AT命令：
AT&F '恢复出厂设置'
ATE1 '打开回显'
ATX3 '禁止'MODEM'对盲音和拨号音的检测'
ATD '开始连接'
B型：
问题就在B型的“RJ_Modem”上.
我先对‘RJ-Modem’初始化：
1)设置DTR,RTS为低电平。
2)输入以下命令：
AT&F '恢复出厂设置'
ATE1 '打开回显'
ATX3 '禁止'MODEM'对盲音和拨号音的检测'
然后输入连接命令：
ATD '开始连接'
我用'ARM'发送'AT'命令给“RJ_Modem”如果发送无需连接的AT指令，如：AT；AT&F；AT&Y0；AT&Z0=12345； RJ_Modem都能正常运行（返回OK
）,但是运行命令：'ATD'(拨号命令) 或者 'ATA'(手工应答)，在电话线上监测不到信号（用超级终端在PC机上往TP-LINK－MODEM
发'ATD'或'ATA'时，可以在电话线上可以检测到信号），但是可以检测到'RJ-Modem'的13脚（SPEKR）有信号。
请大家提提看法，看看哪里出了问题？是初始化部分还是那里出了问题？![]() |
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