Sun Microsystems Interface Adapter manual Configuring Internal or External Clocking

Configuring Internal or External Clocking

To configure an RS-449 port to provide transmit clocking for itself as well as receive clocking for the other end of the link, set the txc (transmit clock) and rxc (receive clock) parameters in hsip_init to baud and rxc, respectively. For example, the following hsip_init command sets the data rate of the first SunHSI/U serial port to 9600 bps and sets the clocking as described:

#hsip_init hihp0 9600 txc=baud rxc=rxc

You enter such a command at both ends of a link if both sides are supplying clocking.

If a Sun system is at each end of a link and one system supplies clocking for both sides, enter the following command on the system that is not supplying the clocking:

#hsip_init hihp0 9600 txc=txc rxc=rxc

Building the Null Modem Cable

To build a null modem cable, you can configure your own cable or use a standard cable with an adapter box.

Note – Be sure to use shielded, twisted-pair wire when building a null modem cable.

If you decide to use an adapter box, be sure to obtain an adapter that allows you to change the pin configurations. Preconfigured adapters generally do not work with synchronous protocols because they do not handle clock signals correctly.

30 Sun PCI High Speed Quad Port Serial Interface Adapter User’s Guide • December 2005