Westermo MR Series - Manual (Page 433)

433 6622-3201
Web Interface and Command Line Reference Guide www.westermo.com
X.21 25-Pin to 15-Pin Crossover Cable – External Clock 21.1.5
This is normally the cable to use to connect the Westermo to an X.21 leased line. Use this cable
when the Westermo is the clock sink or configured as “external clock”.
25-way D - Westermo Side 15-way D
13
25 14
1 1
9 15
8
Signal Pin # (DCE) Pin # (DTE) Signal
Frame Ground (Case) Shield Shield Frame Ground (Case)
TxDA 2 4 RxDA
RxDA 3 2 TxDA
CTLA 4 5 INDA
INDA 5 3 CTLA
GND 7 8 GND
CLKB 11 13 CLKB
INDB 13 10 CTLB
TxDB 14 11 RxDB
RxDB 16 9 TxDB
CTLB 19 12 INDB
CLKA 24 6 CLKA
N.B. Frame Ground is optional.
Note:
When operating an X.21 (RS-422) link Synchronously it is necessary to fit termination resistors
to each signal pair at the receiving end. The Westermo already has in-built terminating resistors,
but terminating resistors will need to be fitted between the TxDA & TxDB pins, CLKA & CLKB
pins and CTLA & CTLB pins at the DTE.