P300H P300 Series Modem Installation and Operating Handbook Page 173
P1440 IN RS232 MODE
The P1440 is the standard interface supplied with the P300 Series Modem. If
RS232
is selected under
ݸ¿²¹»
,
Ì»®®óײ¬º½
,
Û´»½¬®·½¿´
then the following interface description applies.
Min
Req
Signal Description
RS232
Name
Circuit
Number
25 pin
37 pin
Electrical
Levels
A
B
A
B
DATA CIRCUIT TOWARDS MODEM (TX)
Clock In
DA
113
17
24
RS232
Data In
RS232
BA
103
2
4
Sig
`
Valid In
CA
105
4
7
RS232
Sig Accpt
`
d Out
CB
106
5
9
RS232
Int
`
Tx Clock Out
DB
114
15
5
RS232
DATA CIRCUIT FROM MODEM (RX)
Clock Out
DD
115
17
8
RS232
Data Out
BB
104
3
6
RS232
Sig
`
Valid Out
CF
109
8
13
RS232
COMMON LINES
Signal Ground
AB
102
7
19, 20, 21
Ground
Shield/Protective ground
SHIELD
101
1
1
Screen
Device (DTE) Ready In
CD
108
20
12
RS232
Device (DCE) Ready Out
CC
107
6
11
RS232
Local Loop In
LL
141
18
10
RS232
Remote Loop In
RL
140
21
14
RS232
The
maximum data rate
is 100kbps (over good quality screened cable), but this rate is reduced as the connecting
cables extend beyond 10m. As an estimate, assume the maximum rate halves as the distance doubles (ie 50kbps to
20m, 25kbps to 40m etc). NOTE this is a synchronous RS232 interface if you need an asynchronous interface
please contact the factory
.
The
input clock/data phase
is selected automatically, reporting a `
Data Marginal
` warning whenever it
has to switch phase. If the modem reports Data Marginal frequently then this is not a modem fault but an
indication that you have a clocking problem external to the modem (ie changing clock/data phase, a
problem which would otherwise have caused untraceable data errors). With the Tx Clocking Set to
̨
Ý´±½µ ײ
the `Data In` signal is checked against the `Clock In` signal. With the Tx Clocking Set to
ײ¬»®²¿´
or
Ψ
the `Data In` signal is checked against the `In` Tx Clk Out` signal.
Note that although there are both 25-pin EIA530 pinout and 37 pin RS449 pinout connectors on the rear
panel, these are simply connected in parallel.
Do not use both connectors
at the same time. The
EIA530 connector is pin compatible with the standard 25-pin RS232 interface.
By selecting
ݸ¿²¹»
,
Ì»®®óײ¬º½
,
ݱ²¬®±´ Ô·²»-
it is possible to configure the modem to raise an alarm if
either the `Sig Valid In` line (CA) or `Device (DTE) Ready In` line (CD) switch to the inactive state. It is
also possible to configure the Tx carrier to be switched on and off by the `Sig Valid In` line (CA) by
selecting
ݸ¿²¹»
,
̨
,
Ó±¼«´¿¬±®
,
Ý¿®®·»®
,
ÎÌÍóݱ²¬®±´´»¼
.
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