P300H P300 Series Modem Installation and Operating Handbook Page 171
P1440 IN RS422 MODE
The P1440 is the standard interface supplied with the P300 Series Modem. If
RS422
is selected under
ݸ¿²¹»
,
Ì»®®óײ¬º½
,
Û´»½¬®·½¿´
then the following interface description applies.
Min
Req
Signal Description
RS422
Name
Circuit
Number
25 pin
37 pin
Electrical
Levels
A
B
A
B
DATA CIRCUIT TOWARDS MODEM (TX)
Clock In
TT
113
24
11
17
35
RS422
Data In
SD
103
2
14
4
22
RS422
Sig
`
Valid In
RS
105
4
19
7
25
RS422
Sig Accpt
`
d Out
CS
106
5
13
9
27
RS422
Int
`
Tx Clock Out
ST
114
15
12
5
23
RS422
DATA CIRCUIT FROM MODEM (RX)
Clock Out
RT
115
17
9
8
26
RS422
Data Out
RD
104
3
16
6
24
RS422
Sig
`
Valid Out
RR
109
8
10
13
31
RS422
COMMON LINES
Signal Ground
SG
102
7
19, 20, 21
Ground
Shield/Protective ground
PG
101
1
1
Screen
Device (DTE) Ready In
TR
108
23
20
12
30
RS422
Device (DCE) Ready Out
DM
107
6
22
11
29
RS422
Local Loop In
LL
141
18
10
RS232
Remote Loop In
RL
140
21
14
RS232
The
maximum data rate
is 10Mbps (over good quality twisted pair 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 5Mbps to 20m, 2.5Mbps to 40m etc).
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 `Int` 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.
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 (RS) or `Device (DTE) Ready In` line (TR) 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 (RS) by
selecting
ݸ¿²¹»
,
̨
,
Ó±¼«´¿¬±®
,
Ý¿®®·»®
,
ÎÌÍóݱ²¬®±´´»¼
.