Appendix C. IR- X.21B Interface Module ASM-20 Installation and Operation Manual
C-4 INT/RCV Mode 6/4/99 13:18
IR-X.21
FIFO
Buffer
Transmit Data from DTE
External Timing from DTE
Receive Data to DTE
(Jumpers 2,9)
(Jumpers 6,13)
(Jumpers 4,11)
DB Connector
RD
RC
TC
TD
MODEM (EXT)
Figure C-4 EXT Mode Timing Block
C.6 INT/RCV Mode
This mode is used in applications where the IR-X.21B side uses the clock
signal from the modem link. This mode is used mainly when the attached
equipment has an IR-X.21 interface, but no ability to produce clock signals.
The module has a 16-bit FIFO buffer to compensate for the phase delay
introduced by the X.21 device. Figure C-5 illustrates the buffer connection
and the required application setup. When the modem’s clock mode is INT
or RCV, the JP2 jumper must be set to INT/RCV (see Figure C-3).
IR-X.21
Signal Timing to DTE
Transmit Data from DTE
(Jumpers 6,13)
(Jumpers 2,9)
DB Connector
MODEM (INT or RCV)
TC
RD
RC
TD
Receive Data to DTE
(Jumpers 4,11)
FIFO
Buffer
Figure C-5 INT/RCV Mode Timing Block