RFL SMX3 / 21
Page 17 of 22
Issue 1.4
User Manual
08 June 2009
DIP Switch 6 settings
:
Switch 6 – Clock and Timing Configuration
8 7
6
5
4
3 2
1
RTS Time Out
Aggregate Speed
kbit/s
Clock
Source
Not Used
Port C
Port B
00 = 64
00 = X.21 Port
0 = Disabled
0 = Disabled
01 = 128
01 = Concat port
1 = Enabled
1 = Enabled
10 = 192
10 = Master
11 = 256
11 = Auto
•
V.24 Port RTS Timeout:
Normally set to Enabled for a polling system.
When Enabled, the effect of RTS ON is limited to 2 seconds, i.e. CTS and remote
DCD turn OFF and TxD is blocked. In order to recover, RTS
presented
to
the
port has to turn off and remain off for 2 seconds. This feature is to prevent a faulty
RTU of a SCADA system from interfering with traffic on the rest of the SCADA
system.
Do not set to Enabled when port is dedicated for use with MPR or other protection
relay, or when testing with a data tester.
•
Timing source: X.21 Port, Concatenation Port, Master, Auto,
X.21 is the normal setting for applications where the SMX3/21 X.21 port is connected
to a service synchronised with the network master clock.
Concatenation Port is the setting used when an X.21 link needs to be synchronised to
the network master clock signal from an
adjacent
link. Signal timing is via the
concatenation port from the co-located unit. When used in conjunction with the
modes Enabled as DCE, (or Enabled as DTE + Signal Timing X), the timing signal
received from the concatenation port will be output onto the X.21port.
Master is used where it is necessary for timing to be generated internally for SMX/21.
The clock is generated internally and transmitted on X on either the X.21 Aggregate
port or the Concatenation port. It is used with Enabled as DCE mode, (generally for
test purposes only), and for Enabled as Concat mode where two units are
interconnected via concatenation ports and the X.21 network service is unavailable.
Auto locks timing to the X.21 port as a priority and to the Concatenation port if that
fails. When timing is locked to the Concatenation port and an acceptable clock
appears on the X.21 port, timing source will revert to the X.21 port. This function has
a special application for East-West applications where both X.21 and Concatenation
ports receive network master clock timing.
This is not used when concatenating
consecutive point to point links using the concatenation port to connect to an co-
located SMX3/21.
•
Aggregate Speed: 64, 126, 192, 256 kbits/s
Set to match the network clock speed. For X.21 networks operating at n = 1, set to
64kbits/s. (Note: when using Channel A (X.21 port), it is not possible to use 64 or
192kbits/s, but it is possible to use the V.24 ports alone)
