RFL SMX3 / 21
Page 10 of 22
Issue 1.4
User Manual
08 June 2009
8. X.21 Data Port (Channel A)
The port for Channel A is a DB15 female connector; it is configured as DCE.
Channel A Port Pin-out – D15F on chassis (DCE)
Circuit
Pin A
Pin B
Direction
Notes
T Transmit
Data
2
9 Input
R Receive
Data
4 11 Output
C
Control
3
10
Input
see Note below
I
Indication
5
12
Output
See Note below
S Signal
Element
Timing
6
13
Output
Timing signal transmitted
to network
G Ground
8 15
Screen / Drain
Must be earthed to shell
Transceivers are specified to ± 15kV IEC1000-4-2 air discharge ESD protection and
port connections are additionally protected by Tranzorb type arrays.
Data received at the Channel A port is always terminated; it cannot be concatenated
across the concatenation link.
S is normally synchronised to network timing but in the event of this being
unavailable runs from an internal source within the SMX.
Note:
When DIP SW 1-2 is set to Local, I is ON when the channel is legally configured, the
aggregate is running and in sync, in which case C is ignored
When DIP SW 1-2 is set to Remote, I is ON when the channel is legally configured,
the aggregate is running and in sync, and C is received from the remote end.
