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Question Difficulty with 3COM 3CXEM556BC Megahertz modem 

Forum: PCMCIA Multifunction Card Issues
Date: 2000, Apr 14
From: Alexander Russell Alex_Russell

Hi,

I'm having some trouble with my 3Com 3CXEM556BC on a Dell Inspiron 7500 running RedHat 6.2. This is a multifunction card: it's the serial modem half of the card which is giving me trouble. The card is properly identified, and the modem seems to work just fine at low bandwidth. As soon as I begin to fetch a large file, say, the transmission quits after about 100k. (This is at 28.8kbps.) I can restart the download and witness the same behavior over and over. (Unfortunately, I am not sure if this represents loss of received or (un)sent packets.)

I'm not sure what to try next. Many thanks!

Alex Russell

Details:

The card seems to be identified correctly:

[root@hermes acr]# cardctl ident
Socket 0:
  no product info available
Socket 1:
  product info: "3Com", "Megahertz 3CXEM556", "LAN + 56k Modem", ""
  manfid: 0x0101, 0x0035
  function: 0 (multifunction)
[root@hermes acr]

Setserial seems reasonably happy:
[root@hermes acr]# setserial -ga /dev/ttyS1
/dev/ttyS1, Line 1, UART: 16550A, Port: 0x02f8, IRQ: 3
	Baud_base: 115200, close_delay: 50, divisor: 0
	closing_wait: 3000, closing_wait2: infinte
	Flags: spd_normal skip_test

(The serial half and the ethernet half do seem to be sharing an interrupt: is this ok?)

[root@hermes acr]# cat /proc/interrupts
           CPU0       
  0:     112112          XT-PIC  timer
  1:        715          XT-PIC  keyboard
  2:          0          XT-PIC  cascade
  3:        523          XT-PIC  3c589_cs
  5:       4527          XT-PIC  ESS Maestro 2E
  8:          1          XT-PIC  rtc
 11:          8          XT-PIC  i82365
 12:       5023          XT-PIC  PS/2 Mouse
 13:          1          XT-PIC  fpu
 14:     106360          XT-PIC  ide0
 15:       4921          XT-PIC  ide1
NMI:          0
[root@hermes acr]# 

Finally, here is the initialization log produced at boot time. (I should mention that in this represents a boot when the ethernet is not hooked up.)

Apr 14 16:10:08 hermes pcmcia: Starting PCMCIA services:
Apr 14 16:10:09 hermes pcmcia:  modules
Apr 14 16:10:09 hermes kernel: Linux PCMCIA Card Services 3.1.14 
Apr 14 16:10:09 hermes kernel:   kernel build: 2.2.14-5.0 #1 Tue Mar 7 21:07:39 EST 2000 
Apr 14 16:10:09 hermes kernel:   options:  [pci] [cardbus] [apm] [pnp] 
Apr 14 16:10:09 hermes kernel: PCI routing table version 1.0 at 0xfdf50 
Apr 14 16:10:09 hermes kernel:   00:04.0 -> irq 11 
Apr 14 16:10:09 hermes kernel:   00:04.1 -> irq 11 
Apr 14 16:10:09 hermes kernel: PnP: PNP BIOS installation structure at 0xc00f7210 
Apr 14 16:10:09 hermes kernel: PnP: PNP BIOS version 1.0, entry at f0000:a776, dseg at 400 
Apr 14 16:10:09 hermes kernel: Intel PCIC probe:  
Apr 14 16:10:09 hermes kernel:   TI 1225 rev 01 PCI-to-CardBus at slot 00:04, mem 0x68000000 
Apr 14 16:10:09 hermes kernel:     host opts [0]: [ring] [serial pci & irq] [pci irq 11] [lat 168/32] [bus 32/34] 
Apr 14 16:10:09 hermes kernel:     host opts [1]: [ring] [serial pci & irq] [pci irq 11] [lat 168/32] [bus 35/37] 
Apr 14 16:10:09 hermes kernel:     ISA irqs (scanned) = 3,4,9,10 PCI status changes 
Apr 14 16:10:09 hermes pcmcia:  cardmgr.
Apr 14 16:10:09 hermes rc: Starting pcmcia succeeded
Apr 14 16:10:09 hermes cardmgr[393]: starting, version is 3.1.14
Apr 14 16:10:09 hermes inet: inetd startup succeeded
Apr 14 16:10:09 hermes cardmgr[393]: watching 2 sockets
Apr 14 16:10:09 hermes kernel: cs: IO port probe 0x1000-0x17ff: clean. 
Apr 14 16:10:09 hermes kernel: cs: IO port probe 0x0100-0x04ff: clean. 
Apr 14 16:10:09 hermes kernel: cs: IO port probe 0x0a00-0x0aff: clean. 
Apr 14 16:10:09 hermes cardmgr[393]: initializing socket 1
Apr 14 16:10:09 hermes kernel: cs: memory probe 0xa0000000-0xa0ffffff: clean. 
Apr 14 16:10:09 hermes cardmgr[393]: socket 1: 3Com/Megahertz 3CXEM556 Ethernet/Modem
Apr 14 16:10:10 hermes inetd[407]: auth/tcp: bind: Address already in use
Apr 14 16:10:10 hermes inetd[407]: extra conf for service linuxconf/tcp (skipped) 
Apr 14 16:10:10 hermes lpd[421]: restarted
Apr 14 16:10:10 hermes lpd: lpd startup succeeded
Apr 14 16:10:10 hermes cardmgr[393]: executing: 'insmod /lib/modules/2.2.14-5.0/pcmcia/3c589_cs.o'
Apr 14 16:10:10 hermes cardmgr[393]: executing: 'insmod /lib/modules/2.2.14-5.0/pcmcia/serial_cs.o'
Apr 14 16:10:10 hermes kernel: eth0: 3Com 3c589, io 0x300, irq 3, hw_addr 00:00:86:32:6C:11 
Apr 14 16:10:10 hermes kernel:   8K FIFO split 5:3 Rx:Tx, auto xcvr 
Apr 14 16:10:10 hermes kernel: tty01 at 0x02f8 (irq = 3) is a 16550A 
Apr 14 16:10:10 hermes cardmgr[393]: executing: './network start eth0'
Apr 14 16:10:10 hermes keytable: Loading keymap: 
Apr 14 16:10:10 hermes keytable: Loading /usr/lib/kbd/keymaps/i386/qwerty/us.kmap.gz
Apr 14 16:10:10 hermes cardmgr[393]: executing: './serial start ttyS1'

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None Re: Question: Difficulty with 3COM 3CXEM556BC Megahertz modem

Re: Question Difficulty with 3COM 3CXEM556BC Megahertz modem (Alexander Russell)
Date: 2000, Apr 14
From: David Hinds <dhinds@pcmcia.sourceforge.org>

What are you using for downloads?  (is this a PPP or slip connection,
or something else?)  Can you vouch that you have a good quality phone
line?

When you say you can restart the download, what does that mean,
exactly?  Do you hang up and start a new connection?  Or can you
restart it without dropping your current call?

What about the ethernet port?  Have you tested that?

I would probably try bumping the card onto several other interrupts to
see if that makes any difference.

-- Dave

More More information on 3com 3CXEM556BC Problem

Re: None Re: Question: Difficulty with 3COM 3CXEM556BC Megahertz modem (David Hinds)
Date: 2000, Apr 14
From: Alexander Russell Alex_Russell

Hi,

	Wow-thanks for your fast response!

	I forgot to say a couple of things in my last message:

	1. The hardware works fine under Win98, so I believe 
	that the modem functions and that the phone line is
	clean.

	2. The LAN behavior of the card is just dandy. I can
	pull about 820k/sec on my local ethernet, which is
	roughly competitive with the other machines around
	here.

	3. I am using a PPP connection. Here is the behavior I observe:
	I log on. All is well. Under light load it performs as
	I would expect. As soon as I do something which
	saturates the channel (i.e., download a large file),
	after receipt of about 60-100k the download quits. If
	I watch the pretty graphs that is made by RedHat's usernet
	window, I can see the load climb up to full
	throughput (about 3k/sec) and then suddently drop off.
	This is followed by some pings at regular intervals.
	If I cancel the download (but remain connected) and
	begin again, I observe the same behavior.

	I will experiment with the interrupts as you suggest.

	Thanks very much for your help,

	Incidentally, I'd like to purchase a Cardbus 100bT
	network card. Which seems is the most favourable for
	the pcmcia package these days?

Thanks again,

Alex Russell

None Re: More: More information on 3com 3CXEM556BC Problem

Re: More More information on 3com 3CXEM556BC Problem (Alexander Russell)
Date: 2000, Apr 28
From: David Hinds <dhinds@pcmcia.sourceforge.org>

I wonder if it could either be a modem configuration issue, or a
problem in the kernel PPP code that is causing the connection to
stall.

A few random things to try:

- See if the stalls still happen if you do "setserial /dev/modem irq 0"
- See if it matters if eth0 is "up" while you're using PPP
- Try setting CORE_OPTS="io_speed=200" in your PCMCIA startup options

-- Dave
Difficulty with 3COM 3CXEM556BC Megahertz modem


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