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dhb(4) [ultrix man page]

dhb(4)							     Kernel Interfaces Manual							    dhb(4)

Name
       dhb - DHB32 communications multiplexer

Syntax
       device dmb0 at vaxbi? node? flags 0x????
	    vector dmbsint dmbaint dmblint

Description
       A  DHB32  device  provides  16  asynchronous  communication lines with full modem control.  The DHB32 and the DMB32 share a common software
       device driver.  For this reason, the configuration line is the same for both the DHB32 and DMB32.

       Each line attached to a DHB32 serial line port behaves as described in Input and output for each line can independently be set  to  run	at
       any of 16 speeds.  See for the encoding.

       Bit i of flags may be specified for a to say that a line should be treated as a hardwired connection with carrier always present.  If bit i
       of flags is not set, the line will operate under full modem control.  Modem lines will operate in accordance to the  CD	(carrier  detect),
       DSR  (data  set	ready) and CTS (clear to send) leads.  Thus, specifying ``flags 0x0004'' in the specification of would cause line 2 on the
       DHB32 to be treated as hardwired with carrier always present.  In this example, the remainder of the lines will be modem control lines.

Diagnostics
       dmbinit: async lines unavailable
       This message is produced at system boot time if the DHB32 fails its internal self test indicating that the asynchronous lines  have  failed
       to configure.

       dmb%d: fifo overflow
       The character input fifo overflowed before it could be serviced.  This can happen if the CPU is running with elevated priority for too long
       a period of time.  Overflow errors may indicate that configuration constraints have been reached.

       dmb%d: DMA Error. tbuf = 0x%x
       A DMA output transfer failed.  This problem can result from a memory error or an invalid pte (page table entry).  For a description of  the
       error code in the ``tbuf'' register. See the DHB32 documentation.

       dmb%d: DMB Hardware Error. TX.DMA.START failed
       The failed to clear the start bit.  Normally, this is cleared to signal that a DMA transfer has completed.

       dmb%d: Modem Error. tbuf = 0x%x
       Indicates a problem with a modem or its cable.  For a description of the error code in the ``tbuf'' register. See the DHB32 documentation.

       dmb%d: Internal Error. tbuf = 0x%x
       Indicates  that	the  DHB32  detected  an internal error.  For a description of the error code in the ``tbuf'' register. See the DHB32 User
       Guide.

Files
       (modem lines only)

See Also
       tty(4), MAKEDEV(8), dmbsp(4)

																	    dhb(4)

Check Out this Related Man Page

cxa(4)							     Kernel Interfaces Manual							    cxa(4)

Name
       cxa - CXA16 communications interface

Syntax
       device dhu0 at uba0 csr 0160440 flags 0xffff vector dhurint dhuxint

Description
       A CXA16 provides 16 data-leads-only communication lines with no modem control.  The CXA16 conforms to RS423A.  The device behaves and looks
       just like a DHV11 (with the exception of modem control and number of lines) and is specified in the configuration line the same as a  DHV11
       device.	 Each line attached to the CXA16 communications multiplexer behaves as described in and can be set to run at any of 16 speeds; see
       for the encoding.

       A flags field of 0xffff must be used to specify that all lines are to operate as hardwired.  This is done to prevent the  line  from  being
       treated as a modem control line.

       The dhu driver normally interrupts on each input character.  The and devices operate under the control of the driver.

Diagnostics
       dhu%d: receive fifo overflow
       The  character input fifo overflowed before it could be serviced.  This can happen if a hard error occurs when the CPU is running with ele-
       vated priority, as the system then prints a message on the console with interrupts disabled.  This can cause a few input characters  to	be
       lost to users.  It is not serious.

       dhu%d:%d DMA ERROR
       A  DMA  transfer  error	has  occurred.	 The unit number and line number are printed.  This means that the channel indicated has failed to
       transfer DMA data within 10.7 microseconds of the bus request being acknowledged or that there is a memory parity error.  This may cause  a
       few output characters to be lost.

       dhu%d: DIAG. FAILURE
       This indicates that the internal diagnostics have detected an error.

       dhu%d: DHU HARDWARE ERROR.  TX.DMA.START failed
       The failed to clear the start bit.  Normally, this is cleared to signal that a DMA transfer has completed.

Files
See Also
       tty(4), MAKEDEV(8)

																	    cxa(4)
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