Service Manual

NAME DESCRIPTION CHARACTERISTIC
DP_DTR/ Data Terminal Ready Host ready signal
DP_RXD Receive Data Input data to the modem
DP_CTS/ Clear to Send Modem output signal
GND Signal Ground Signal ground
4.2.2 Signal level of RXD/TXD
RS232 PHONE
TX
•
1
RX
•
2
TX
•
4
RX
•
3
V
MAX
= 7.68V
V
MIN
= -7.68V
V
MAX
= 6.00V
V
MIN
= -5.84V
V
MAX
= 3.00V
V
MIN
= 0V
V
MAX
= 4.88V
V
MIN
= 0V
[Figure 4-2] Signal Level of RXD, TXD
4.3 LED State Indication
Name Enable Description
1 D17(SMS) Low Shot Message Service
2 D1(BUSY) Low State that Data transmit and receive between DTE and
DCE
3 D2(IDLE) Low Stable State
PC
RS232
TX
RX
•
1
•
3
•
2
•
4
Phone
+3V
+3V
V
out
= 2.8V
MSM_input
MSM_output
LT
MAXIM207
+5V