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Re: [hylafax-users] fcs error by sending to remote panasonic

On 2004.07.16 08:05 Borut Kurnik wrote:

Jul 13 14:12:25.33: [14344]: <-- [9:AT+FRH=3\r]
Jul 13 14:12:25.35: [14344]: --> [7:CONNECT]
Jul 13 14:12:26.03: [14344]: --> HDLC<25:FF C0 02 0C 2C EC AC 0C 4C 2C
04 04 04 04 04 04 04 04 04 04 04 04 04 D0 89>
Jul 13 14:12:26.03: [14344]: --> [2:OK]
Jul 13 14:12:26.03: [14344]: REMOTE CSI "4205740"
Jul 13 14:12:26.03: [14344]: <-- [9:AT+FRH=3\r]
Jul 13 14:12:26.05: [14344]: --> [7:CONNECT]
Jul 13 14:12:26.38: [14344]: --> HDLC<11:FF C8 01 00 72 1D 01 01 88 A9
FC>
Jul 13 14:12:26.38: [14344]: --> [5:ERROR]
Jul 13 14:12:26.38: [14344]: MODEM Command error
Jul 13 14:12:26.38: [14344]: FCS error

This means that the DIS signal that we were receiving is corrupt. The two FCS bytes at the end of the signal do not "check out" against the rest of the signal. In the prologue HylaFAX deals with this by waiting 200 ms and then awaiting the receiver to resend the prologue signals (hopefully they come through properly).

Jul 13 14:12:26.38: [14344]: DELAY 200 ms
Jul 13 14:12:26.58: [14344]: <-- [9:AT+FRH=3\r]
Jul 13 14:12:26.60: [14344]: --> [7:CONNECT]
Jul 13 14:12:26.60: [14344]: --> [2:10 03]
Jul 13 14:12:26.60: [14344]: --> [5:ERROR]
Jul 13 14:12:26.60: [14344]: MODEM Command error
Jul 13 14:12:26.60: [14344]: FCS error

The fact that we only got <DLE><ETX> ("10 03") means that we caught the tail-end of some signal, and given what happened just 0.22 s before, this isn't surprising.

Jul 13 14:12:26.60: [14344]: DELAY 200 ms
Jul 13 14:12:26.80: [14344]: <-- [9:AT+FRH=3\r]
Jul 13 14:12:26.82: [14344]: --> [7:CONNECT]
Jul 13 14:12:26.83: [14344]: --> [16:03 00 6C 56 00 A0 6C 56 00 A0 6C
56
00 A0 6C 56]
Jul 13 14:12:26.83: [14344]: --> [5:ERROR]
Jul 13 14:12:26.83: [14344]: MODEM Command error
Jul 13 14:12:26.83: [14344]: FCS error

This is unfortunate. It would appear that the 200 ms delay is a bit too long in this instance. In any case, we see another corrupt signal.

Jul 13 14:12:26.83: [14344]: DELAY 200 ms
Jul 13 14:12:27.03: [14344]: <-- [9:AT+FRH=3\r]
Jul 13 14:12:34.03: [14344]: --> [0:]
Jul 13 14:12:34.03: [14344]: MODEM <Empty line>
Jul 13 14:12:34.03: [14344]: MODEM TIMEOUT: waiting for v.21 carrier
Jul 13 14:12:34.04: [14344]: --> [2:OK]

This happens because both sender and receiver are waiting a signal from each other and neither one is sending one.

Jul 13 14:12:34.04: [14344]: DELAY 200 ms
Jul 13 14:12:34.24: [14344]: <-- [9:AT+FRH=3\r]
Jul 13 14:12:36.31: [14344]: --> [7:CONNECT]
Jul 13 14:12:38.14: [14344]: --> HDLC<45:FF C0 04 00 00 9E 00 00 00 41
F0 90 48 00 08 A0 40 A9 13 11 01 01 80 80 92 40 92 B2 0A 04 D2 32 92
B2
82 2A 04 B2 F2 CA C2 F2 C0 1F 98>
Jul 13 14:12:38.14: [14344]: --> [2:OK]
Jul 13 14:12:38.14: [14344]: REMOTE NSF "00 00 79 00 00 00 82 0F 09 12
00 10 05 02 95 C8 88 80 80 01 01 49 02 49 4D 50 20 4B 4C 49 4D 41 54
20
4D 4F 53 43 4F 03 F8"
Jul 13 14:12:38.14: [14344]: NSF remote fax equipment: Panasonic
Jul 13 14:12:38.14: [14344]: NSF remote station ID: "XXXXXXXXXXXXX"
Jul 13 14:12:38.14: [14344]: <-- [9:AT+FRH=3\r]
Jul 13 14:12:38.16: [14344]: --> [7:CONNECT]
Jul 13 14:12:38.84: [14344]: --> HDLC<25:FF C0 02 0C 2C EC AC 0C 4C 2C
04 04 04 04 04 04 04 04 04 04 04 04 04 D0 89>
Jul 13 14:12:38.84: [14344]: --> [2:OK]
Jul 13 14:12:38.84: [14344]: REMOTE CSI "4205740"
Jul 13 14:12:38.84: [14344]: <-- [9:AT+FRH=3\r]
Jul 13 14:12:38.86: [14344]: --> [7:CONNECT]
Jul 13 14:12:39.18: [14344]: --> HDLC<11:FF C8 01 00 72 1D 01 01 88 A9
FF>
Jul 13 14:12:39.18: [14344]: --> [2:OK]
Jul 13 14:12:39.18: [14344]: REMOTE best rate 9600 bit/s
Jul 13 14:12:39.18: [14344]: REMOTE max page width 1728 pixels in 215
mm
Jul 13 14:12:39.18: [14344]: REMOTE max unlimited page length
Jul 13 14:12:39.18: [14344]: REMOTE best vres 7.7 line/mm
Jul 13 14:12:39.18: [14344]: REMOTE best format 1-D MR
Jul 13 14:12:39.18: [14344]: REMOTE best 20 ms, 10 ms/scanline

Beautiful, this time all signals were received properly. Notice how resiliant fax protocol can be. :-)

Jul 13 14:12:39.18: [14344]: USE 9600 bit/s
Jul 13 14:12:39.18: [14344]: USE 20 ms, 10 ms/scanline
Jul 13 14:12:39.18: [14344]: SEND file "docq/doc113.ps;00"
Jul 13 14:12:39.19: [14344]: USE page width 1728 pixels in 215 mm
Jul 13 14:12:39.19: [14344]: USE unlimited page length
Jul 13 14:12:39.19: [14344]: USE 3.85 line/mm
Jul 13 14:12:39.19: [14344]: USE 1-D MR
Jul 13 14:12:39.19: [14344]: SEND training at v.29 9600 bit/s
Jul 13 14:12:39.19: [14344]: <-- [9:AT+FTH=3\r]
Jul 13 14:12:39.38: [14344]: --> [7:CONNECT]
Jul 13 14:12:39.38: [14344]: <-- HDLC<23:FF C0 C2 4C CC 4C AC 0C 0C CC
8C 0C 6C 1C CC D4 04 04 04 04 04 04 04>
Jul 13 14:12:39.41: [14344]: --> [7:CONNECT]
Jul 13 14:12:39.41: [14344]: <-- HDLC<6:FF C8 C1 00 60 10>
Jul 13 14:12:41.35: [14344]: --> [2:OK]
Jul 13 14:12:41.35: [14344]: <-- [9:AT+FTS=7\r]
Jul 13 14:12:41.44: [14344]: --> [2:OK]
Jul 13 14:12:41.44: [14344]: <-- [10:AT+FTM=96\r]
Jul 13 14:12:41.76: [14344]: --> [7:CONNECT]
Jul 13 14:12:43.29: [14344]: --> [2:OK]
Jul 13 14:12:43.29: [14344]: <-- [9:AT+FRH=3\r]
Jul 13 14:12:44.31: [14344]: --> [7:CONNECT]
Jul 13 14:12:45.22: [14344]: --> HDLC<5:FF C8 22 67 DD>
Jul 13 14:12:45.22: [14344]: --> [2:OK]
Jul 13 14:12:45.22: [14344]: SEND training at v.29 7200 bit/s
Jul 13 14:12:45.22: [14344]: <-- [9:AT+FTH=3\r]
Jul 13 14:12:45.42: [14344]: --> [7:CONNECT]
Jul 13 14:12:45.42: [14344]: <-- HDLC<23:FF C0 C2 4C CC 4C AC 0C 0C CC
8C 0C 6C 1C CC D4 04 04 04 04 04 04 04>
Jul 13 14:12:45.45: [14344]: --> [7:CONNECT]
Jul 13 14:12:45.45: [14344]: <-- HDLC<6:FF C8 C1 00 70 10>
Jul 13 14:12:47.39: [14344]: --> [2:OK]
Jul 13 14:12:47.39: [14344]: <-- [9:AT+FTS=7\r]
Jul 13 14:12:47.48: [14344]: --> [2:OK]
Jul 13 14:12:47.48: [14344]: <-- [10:AT+FTM=72\r]
Jul 13 14:12:47.80: [14344]: --> [7:CONNECT]
Jul 13 14:12:49.34: [14344]: --> [2:OK]
Jul 13 14:12:49.34: [14344]: <-- [9:AT+FRH=3\r]
Jul 13 14:12:50.26: [14344]: --> [7:CONNECT]
Jul 13 14:12:51.26: [14344]: --> HDLC<5:FF C8 22 67 DD>
Jul 13 14:12:51.26: [14344]: --> [2:OK]
Jul 13 14:12:51.26: [14344]: SEND training at v.27ter 4800 bit/s
Jul 13 14:12:51.26: [14344]: <-- [9:AT+FTH=3\r]
Jul 13 14:12:51.46: [14344]: --> [7:CONNECT]
Jul 13 14:12:51.46: [14344]: <-- HDLC<23:FF C0 C2 4C CC 4C AC 0C 0C CC
8C 0C 6C 1C CC D4 04 04 04 04 04 04 04>
Jul 13 14:12:51.49: [14344]: --> [7:CONNECT]
Jul 13 14:12:51.49: [14344]: <-- HDLC<6:FF C8 C1 00 50 10>
Jul 13 14:12:53.43: [14344]: --> [2:OK]
Jul 13 14:12:53.43: [14344]: <-- [9:AT+FTS=7\r]
Jul 13 14:12:53.52: [14344]: --> [2:OK]
Jul 13 14:12:53.52: [14344]: <-- [10:AT+FTM=48\r]
Jul 13 14:12:54.54: [14344]: --> [7:CONNECT]
Jul 13 14:12:56.08: [14344]: --> [2:OK]
Jul 13 14:12:56.08: [14344]: <-- [9:AT+FRH=3\r]
Jul 13 14:12:56.66: [14344]: --> [7:CONNECT]
Jul 13 14:12:57.72: [14344]: --> HDLC<5:FF C8 21 57 BE>
Jul 13 14:12:57.72: [14344]: --> [2:OK]
Jul 13 14:12:57.72: [14344]: TRAINING succeeded

Given the amount of difficulty that we experienced with the prologue, it is not surprising that V.29 training did not succeed and that V.27 did.

Jul 13 14:12:57.72: [14344]: DELAY 75 ms
Jul 13 14:12:57.79: [14344]: <-- [10:AT+FTM=48\r]
Jul 13 14:12:58.84: [14344]: --> [7:CONNECT]
Jul 13 14:12:58.84: [14344]: SEND begin page
Jul 13 14:13:11.39: [14344]: SENT 13750 bytes of data
Jul 13 14:13:13.59: [14344]: SENT 624 bytes of data
Jul 13 14:13:13.59: [14344]: SEND 1D RTC
Jul 13 14:13:13.59: [14344]: SEND end page
Jul 13 14:13:22.89: [14344]: --> [2:OK]
Jul 13 14:13:22.89: [14344]: <-- [9:AT+FTS=9\r]
Jul 13 14:13:23.00: [14344]: --> [2:OK]
Jul 13 14:13:23.00: [14344]: SEND send EOP (no more pages or
documents)
Jul 13 14:13:23.00: [14344]: <-- [9:AT+FTH=3\r]
Jul 13 14:13:23.16: [14344]: --> [7:CONNECT]
Jul 13 14:13:23.16: [14344]: <-- HDLC<3:FF C8 F4>
Jul 13 14:13:24.33: [14344]: --> [2:OK]

So we send the page and the post-page message.

Jul 13 14:13:24.33: [14344]: <-- [9:AT+FRH=3\r]
Jul 13 14:13:24.46: [14344]: --> [7:CONNECT]
Jul 13 14:13:24.46: [14344]: --> [2:10 03]
Jul 13 14:13:24.46: [14344]: --> [5:ERROR]
Jul 13 14:13:24.46: [14344]: MODEM Command error
Jul 13 14:13:24.46: [14344]: FCS error

Most likely what is happening here is that we're getting some interference on the line which is making the modem think that it is getting a carrier drop.

Jul 13 14:13:24.46: [14344]: SEND send EOP (no more pages or
documents)
Jul 13 14:13:24.46: [14344]: <-- [9:AT+FTH=3\r]
Jul 13 14:13:24.66: [14344]: --> [7:CONNECT]
Jul 13 14:13:24.66: [14344]: <-- HDLC<3:FF C8 F4>
Jul 13 14:13:25.83: [14344]: --> [2:OK]
Jul 13 14:13:25.83: [14344]: <-- [9:AT+FRH=3\r]
Jul 13 14:13:26.26: [14344]: --> [10:NO CARRIER]
Jul 13 14:13:26.26: [14344]: MODEM No carrier
Jul 13 14:13:26.26: [14344]: SEND send EOP (no more pages or
documents)
Jul 13 14:13:26.26: [14344]: <-- [9:AT+FTH=3\r]
Jul 13 14:13:26.46: [14344]: --> [7:CONNECT]
Jul 13 14:13:26.46: [14344]: <-- HDLC<3:FF C8 F4>
Jul 13 14:13:27.63: [14344]: --> [2:OK]
Jul 13 14:13:27.63: [14344]: <-- [9:AT+FRH=3\r]
Jul 13 14:13:27.76: [14344]: --> [7:CONNECT]
Jul 13 14:13:27.76: [14344]: --> [2:10 03]
Jul 13 14:13:27.76: [14344]: --> [5:ERROR]
Jul 13 14:13:27.76: [14344]: MODEM Command error
Jul 13 14:13:27.76: [14344]: FCS error
Jul 13 14:13:27.76: [14344]: No response to MPS or EOP repeated 3
tries

Well, I'd blame this all on poor line conditions. If you can see the modem manual and try to increase the S-registers that deal with noise thresholds and tolerances that may help. A different modem may also help. (USR modems aren't known for being good fax modems.)

Lee.


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