используем LTR-крейт с подключение по USB
периодически возникает ситуация, когда при включении крейта он не видится программой-сервером: ее значок горит желтым, в ее окошке он не обнаруживается.
если при этом перевоткнуть USB или перезапустить LTR-сервер , то крейт находится.

в логах сервера вот такое (тут и хорошие включения, и пропадания):
[10:52:37] Rescan attached Crates...
[10:52:37] Found usb devices >> total=1  LTRCrates=1
[10:52:37] Crate Info:
[10:52:37] + PIDString=Port_#0006.Hub_#0005
[10:52:37] + DeviceName   =LTR010
[10:52:37] + SerialNumber =3D228404
[10:52:37] + DeviceComment=<Revision>{A}<BurnDate>{10:34 30.7.2010}
[10:52:37] + BootLoaderVersion=1.1.14.1
[10:52:37] + FirmwareVersion=1.6.0.3
[10:52:39] + TTF_FILE=ltr010v3_0_5.ttf
[10:52:39] + FpgaName   =LTR-010
[10:52:39] + FpgaVersion=3.0.5.0
[10:52:39] + FpgaComment=FPGA ACEX1K50 LTR®. L-CARD
[10:52:39] + BoudRate=0x0000  DMAR=7  DMAW=0
[10:52:39] Crate service started.
[10:52:42] RST.XXXX module configuration updated. mconfig=00C2
[10:52:42] WST.XXXX send STOP+RESET+STOP to module. slot=2
[10:52:42] WST.XXXX send STOP+RESET+STOP to module. slot=7
[10:52:42] WST.XXXX send STOP+RESET+STOP to module. slot=8
[10:52:42] RST.XXXX found new module. slot=8  mid=0B0B (LTR11)
[10:52:42] RST.XXXX found new module. slot=2  mid=2B2B (LTR43)
[10:52:42] RST.XXXX found new module. slot=7  mid=2222 (LTR34)
[10:52:42] RST.XXXX change baud rate to 0x0040
[10:52:44] RST.XXXX module configuration updated. mconfig=00C3
[10:52:44] WST.XXXX send STOP+RESET+STOP to module. slot=1
[10:52:44] RST.XXXX found new module. slot=1  mid=2B2B (LTR43)
[10:52:54] WST.XXXX Error async read data size=0
[10:52:54] Read Crate Thread Begin Finishing Work Port_#0006.Hub_#0005
[10:52:54] Read Crate Thread Finished Work Port_#0006.Hub_#0005
[10:52:54] Write Crate Thread Begin Finishing Work Port_#0006.Hub_#0005
[10:52:54] Write Crate Thread Finished Work Port_#0006.Hub_#0005
[10:52:54] Rescan attached Crates...
[10:52:54] Can//'t find any usb device
[10:52:54] Service stoped for crate  >> CSN=3D228404  PIDString=Port_#0006.Hub_#0005  SystemPath=////?//usb#vid_0471&pid_1010#5&21e739f&0&6#{a5dcbf10-6530-11d2-901f-00c04fb951ed}
[11:01:54] Rescan attached Crates...
[11:01:54] Can//'t find any usb device
[11:04:56] Rescan attached Crates...
[11:04:56] Can//'t find any usb device
[11:04:56] Rescan attached Crates...
[11:04:56] Can//'t find any usb device
[11:05:05] Rescan attached Crates...
[11:05:05] Can//'t find any usb device
[11:05:19] Rescan attached Crates...
[11:05:19] Can//'t find any usb device
[11:05:19] Rescan attached Crates...
[11:05:19] Can//'t find any usb device
[11:05:20] Rescan attached Crates...
[11:05:20] Found usb devices >> total=1  LTRCrates=1
[11:05:20] Crate Info:
[11:05:20] + PIDString=Port_#0006.Hub_#0005
[11:05:20] + DeviceName   =LTR010
[11:05:20] + SerialNumber =3D228404
[11:05:20] + DeviceComment=<Revision>{A}<BurnDate>{10:34 30.7.2010}
[11:05:20] + BootLoaderVersion=1.1.14.1
[11:05:20] + FirmwareVersion=1.6.0.3
[11:05:22] + TTF_FILE=ltr010v3_0_5.ttf
[11:05:22] + FpgaName   =LTR-010
[11:05:22] + FpgaVersion=3.0.5.0
[11:05:22] + FpgaComment=FPGA ACEX1K50 LTR®. L-CARD
[11:05:22] + BoudRate=0x0000  DMAR=7  DMAW=0
[11:05:22] Crate service started.
[11:05:23] RST.XXXX module configuration updated. mconfig=00C3
[11:05:23] WST.XXXX send STOP+RESET+STOP to module. slot=1
[11:05:23] WST.XXXX send STOP+RESET+STOP to module. slot=2
[11:05:23] WST.XXXX send STOP+RESET+STOP to module. slot=7
[11:05:23] WST.XXXX send STOP+RESET+STOP to module. slot=8
[11:05:23] RST.XXXX found new module. slot=8  mid=0B0B (LTR11)
[11:05:23] RST.XXXX found new module. slot=2  mid=2B2B (LTR43)
[11:05:23] RST.XXXX found new module. slot=1  mid=2B2B (LTR43)
[11:05:23] RST.XXXX found new module. slot=7  mid=2222 (LTR34)
[11:05:23] RST.XXXX change baud rate to 0x0040
[11:05:52] WST.XXXX Error async read data size=0
[11:05:52] Read Crate Thread Begin Finishing Work Port_#0006.Hub_#0005
[11:05:52] Read Crate Thread Finished Work Port_#0006.Hub_#0005
[11:05:52] Write Crate Thread Begin Finishing Work Port_#0006.Hub_#0005
[11:05:52] Write Crate Thread Finished Work Port_#0006.Hub_#0005
[11:05:52] Rescan attached Crates...
[11:05:52] Can//'t find any usb device
[11:05:52] Service stoped for crate  >> CSN=3D228404  PIDString=Port_#0006.Hub_#0005  SystemPath=////?//usb#vid_0471&pid_1010#5&21e739f&0&6#{a5dcbf10-6530-11d2-901f-00c04fb951ed}
[11:05:59] Rescan attached Crates...
[11:05:59] Found usb devices >> total=1  LTRCrates=1
[11:05:59] Crate Info:
[11:05:59] + PIDString=Port_#0006.Hub_#0005
[11:05:59] + DeviceName   =LTR010
[11:05:59] + SerialNumber =3D228404
[11:05:59] + DeviceComment=<Revision>{A}<BurnDate>{10:34 30.7.2010}
[11:05:59] + BootLoaderVersion=1.1.14.1
[11:05:59] + FirmwareVersion=1.6.0.3
[11:06:01] + TTF_FILE=ltr010v3_0_5.ttf
[11:06:01] + FpgaName   =LTR-010
[11:06:01] + FpgaVersion=3.0.5.0
[11:06:01] + FpgaComment=FPGA ACEX1K50 LTR®. L-CARD
[11:06:01] Can//'t set baudrate && GetModuleDescription after Load FPGA >> CSN=3D228404 TTF_FILE=ltr010v3_0_5.ttf
[11:06:01] Can//'t Init Crate >> SystemPath=////?//usb#vid_0471&pid_1010#5&21e739f&0&6#{a5dcbf10-6530-11d2-901f-00c04fb951ed}
[11:06:01] Rescan attached Crates...
[11:06:01] Found usb devices >> total=1  LTRCrates=1
[11:06:01] Crate Info:
[11:06:01] + PIDString=Port_#0006.Hub_#0005
[11:06:01] + DeviceName   =LTR010
[11:06:01] + SerialNumber =3D228404
[11:06:01] + DeviceComment=<Revision>{A}<BurnDate>{10:34 30.7.2010}
[11:06:01] + BootLoaderVersion=1.1.14.1
[11:06:01] + FirmwareVersion=1.6.0.3
[11:06:05] + TTF_FILE=ltr010v3_0_5.ttf
[11:06:05] + FpgaName   =
[11:06:05] + FpgaVersion=0.0.0.0
[11:06:05] + FpgaComment=
[11:06:05] + BoudRate=0x0000  DMAR=7  DMAW=0
[11:06:05] RST.XXXX module configuration updated. mconfig=0908
[11:06:05] Crate service started.
[11:06:05] WST.XXXX send STOP+RESET+STOP to module. slot=4
[11:06:05] WST.XXXX send STOP+RESET+STOP to module. slot=9
[11:06:05] WST.XXXX send STOP+RESET+STOP to module. slot=12
[11:06:53] WST.XXXX Error async read data size=0
[11:06:53] Read Crate Thread Begin Finishing Work Port_#0006.Hub_#0005
[11:06:53] Read Crate Thread Finished Work Port_#0006.Hub_#0005
[11:06:53] Write Crate Thread Begin Finishing Work Port_#0006.Hub_#0005
[11:06:53] Write Crate Thread Finished Work Port_#0006.Hub_#0005
[11:06:53] Rescan attached Crates...
[11:06:53] Can//'t find any usb device
[11:06:53] Service stoped for crate  >> CSN=3D228404  PIDString=Port_#0006.Hub_#0005  SystemPath=////?//usb#vid_0471&pid_1010#5&21e739f&0&6#{a5dcbf10-6530-11d2-901f-00c04fb951ed}
[11:07:01] Rescan attached Crates...
[11:07:01] Found usb devices >> total=1  LTRCrates=1
[11:07:01] Crate Info:
[11:07:01] + PIDString=Port_#0006.Hub_#0005
[11:07:01] + DeviceName   =LTR010
[11:07:01] + SerialNumber =3D228404
[11:07:01] + DeviceComment=<Revision>{A}<BurnDate>{10:34 30.7.2010}
[11:07:01] + BootLoaderVersion=1.1.14.1
[11:07:01] + FirmwareVersion=1.6.0.3
[11:07:03] + TTF_FILE=ltr010v3_0_5.ttf
[11:07:03] + FpgaName   =LTR-010
[11:07:03] + FpgaVersion=3.0.5.0
[11:07:03] + FpgaComment=FPGA ACEX1K50 LTR®. L-CARD
[11:07:03] + BoudRate=0x0000  DMAR=7  DMAW=0
[11:07:03] Crate service started.
[11:07:03] Rescan attached Crates...
[11:07:03] Found usb devices >> total=1  LTRCrates=1
[11:07:06] RST.XXXX module configuration updated. mconfig=00C2
[11:07:06] WST.XXXX send STOP+RESET+STOP to module. slot=2
[11:07:06] WST.XXXX send STOP+RESET+STOP to module. slot=7
[11:07:06] WST.XXXX send STOP+RESET+STOP to module. slot=8
[11:07:06] RST.XXXX found new module. slot=2  mid=2B2B (LTR43)
[11:07:06] RST.XXXX found new module. slot=8  mid=0B0B (LTR11)
[11:07:06] RST.XXXX found new module. slot=7  mid=2222 (LTR34)
[11:07:06] RST.XXXX change baud rate to 0x0040
[11:07:08] RST.XXXX module configuration updated. mconfig=00C3
[11:07:08] WST.XXXX send STOP+RESET+STOP to module. slot=1
[11:07:08] RST.XXXX found new module. slot=1  mid=2B2B (LTR43)
[11:12:52] WST.XXXX Error async read data size=0
[11:12:52] Read Crate Thread Begin Finishing Work Port_#0006.Hub_#0005
[11:12:52] Read Crate Thread Finished Work Port_#0006.Hub_#0005
[11:12:52] Write Crate Thread Begin Finishing Work Port_#0006.Hub_#0005
[11:12:52] Write Crate Thread Finished Work Port_#0006.Hub_#0005
[11:12:52] Rescan attached Crates...
[11:12:52] Can//'t find any usb device
[11:12:52] Service stoped for crate  >> CSN=3D228404  PIDString=Port_#0006.Hub_#0005  SystemPath=////?//usb#vid_0471&pid_1010#5&21e739f&0&6#{a5dcbf10-6530-11d2-901f-00c04fb951ed}
[11:13:40] Rescan attached Crates...
[11:13:40] Can//'t find any usb device
[11:14:13] Rescan attached Crates...
[11:14:13] Can//'t find any usb device
[11:14:13] Rescan attached Crates...
[11:14:13] Can//'t find any usb device
[11:14:18] Rescan attached Crates...
[11:14:18] Found usb devices >> total=1  LTRCrates=1
[11:14:18] Can//'t execute GetModuleDescription() >> SystemPath=////?//usb#vid_0471&pid_1010#5&21e739f&0&6#{a5dcbf10-6530-11d2-901f-00c04fb951ed}
[11:14:18] Can//'t Init Crate >> SystemPath=////?//usb#vid_0471&pid_1010#5&21e739f&0&6#{a5dcbf10-6530-11d2-901f-00c04fb951ed}
[11:14:18] Rescan attached Crates...
[11:14:18] Found usb devices >> total=1  LTRCrates=1
[11:14:18] Crate Info:
[11:14:18] + PIDString=Port_#0006.Hub_#0005
[11:14:18] + DeviceName   =LTR010
[11:14:18] + SerialNumber =3D228404
[11:14:18] + DeviceComment=<Revision>{A}<BurnDate>{10:34 30.7.2010}
[11:14:18] + BootLoaderVersion=1.1.14.1
[11:14:18] + FirmwareVersion=1.6.0.3
[11:14:20] + TTF_FILE=ltr010v3_0_5.ttf
[11:14:20] + FpgaName   =LTR-010
[11:14:20] + FpgaVersion=3.0.5.0
[11:14:20] + FpgaComment=FPGA ACEX1K50 LTR®. L-CARD
[11:14:20] + BoudRate=0x0000  DMAR=7  DMAW=0
[11:14:20] Crate service started.
[11:14:23] RST.XXXX module configuration updated. mconfig=00C2
[11:14:23] WST.XXXX send STOP+RESET+STOP to module. slot=2
[11:14:23] WST.XXXX send STOP+RESET+STOP to module. slot=7
[11:14:23] WST.XXXX send STOP+RESET+STOP to module. slot=8
[11:14:23] RST.XXXX found new module. slot=2  mid=2B2B (LTR43)
[11:14:23] RST.XXXX found new module. slot=7  mid=2222 (LTR34)
[11:14:23] RST.XXXX change baud rate to 0x0040
[11:14:23] RST.XXXX found new module. slot=8  mid=0B0B (LTR11)
[11:14:25] RST.XXXX module configuration updated. mconfig=00C3
[11:14:25] WST.XXXX send STOP+RESET+STOP to module. slot=1
[11:14:25] RST.XXXX found new module. slot=1  mid=2B2B (LTR43)
[11:14:40] WST.XXXX Error async read data size=0
[11:14:40] Read Crate Thread Begin Finishing Work Port_#0006.Hub_#0005
[11:14:40] Read Crate Thread Finished Work Port_#0006.Hub_#0005
[11:14:40] Write Crate Thread Begin Finishing Work Port_#0006.Hub_#0005
[11:14:40] Write Crate Thread Finished Work Port_#0006.Hub_#0005
[11:14:40] Rescan attached Crates...
[11:14:40] Can//'t find any usb device
[11:14:40] Service stoped for crate  >> CSN=3D228404  PIDString=Port_#0006.Hub_#0005  SystemPath=////?//usb#vid_0471&pid_1010#5&21e739f&0&6#{a5dcbf10-6530-11d2-901f-00c04fb951ed}
[11:14:52] Rescan attached Crates...
[11:14:52] Can//'t find any usb device
[11:15:19] Rescan attached Crates...
[11:15:19] Can//'t find any usb device
[11:15:19] Rescan attached Crates...
[11:15:19] Can//'t find any usb device
[11:15:24] Rescan attached Crates...
[11:15:24] Found usb devices >> total=1  LTRCrates=1
[11:15:24] Crate Info:
[11:15:24] + PIDString=Port_#0006.Hub_#0005
[11:15:24] + DeviceName   =LTR010
[11:15:24] + SerialNumber =3D228404
[11:15:24] + DeviceComment=<Revision>{A}<BurnDate>{10:34 30.7.2010}
[11:15:24] + BootLoaderVersion=1.1.14.1
[11:15:24] + FirmwareVersion=1.6.0.3
[11:15:26] + TTF_FILE=ltr010v3_0_5.ttf
[11:15:26] + FpgaName   =LTR-010
[11:15:26] + FpgaVersion=3.0.5.0
[11:15:26] + FpgaComment=FPGA ACEX1K50 LTR®. L-CARD
[11:15:26] + BoudRate=0x0000  DMAR=7  DMAW=0
[11:15:26] Crate service started.
[11:15:26] Rescan attached Crates...
[11:15:26] Found usb devices >> total=1  LTRCrates=1
[11:15:30] RST.XXXX module configuration updated. mconfig=00C3
[11:15:30] WST.XXXX send STOP+RESET+STOP to module. slot=1
[11:15:30] WST.XXXX send STOP+RESET+STOP to module. slot=2
[11:15:30] WST.XXXX send STOP+RESET+STOP to module. slot=7
[11:15:30] WST.XXXX send STOP+RESET+STOP to module. slot=8
[11:15:30] RST.XXXX found new module. slot=1  mid=2B2B (LTR43)
[11:15:30] RST.XXXX found new module. slot=2  mid=2B2B (LTR43)
[11:15:30] RST.XXXX found new module. slot=8  mid=0B0B (LTR11)
[11:15:30] RST.XXXX found new module. slot=7  mid=2222 (LTR34)
[11:15:30] RST.XXXX change baud rate to 0x0040
[11:15:52] WST.XXXX Error async read data size=0
[11:15:52] Read Crate Thread Begin Finishing Work Port_#0006.Hub_#0005
[11:15:52] Read Crate Thread Finished Work Port_#0006.Hub_#0005
[11:15:52] Write Crate Thread Begin Finishing Work Port_#0006.Hub_#0005
[11:15:52] Write Crate Thread Finished Work Port_#0006.Hub_#0005
[11:15:53] Rescan attached Crates...
[11:15:53] Can//'t find any usb device
[11:15:53] Service stoped for crate  >> CSN=3D228404  PIDString=Port_#0006.Hub_#0005  SystemPath=////?//usb#vid_0471&pid_1010#5&21e739f&0&6#{a5dcbf10-6530-11d2-901f-00c04fb951ed}
[11:16:02] Rescan attached Crates...
[11:16:02] Found usb devices >> total=1  LTRCrates=1
[11:16:02] Crate Info:
[11:16:02] + PIDString=Port_#0006.Hub_#0005
[11:16:02] + DeviceName   =LTR010
[11:16:02] + SerialNumber =3D228404
[11:16:02] + DeviceComment=<Revision>{A}<BurnDate>{10:34 30.7.2010}
[11:16:02] + BootLoaderVersion=1.1.14.1
[11:16:02] + FirmwareVersion=1.6.0.3
[11:16:04] + TTF_FILE=ltr010v3_0_5.ttf
[11:16:04] + FpgaName   =LTR-010
[11:16:04] + FpgaVersion=3.0.5.0
[11:16:04] + FpgaComment=FPGA ACEX1K50 LTR®. L-CARD
[11:16:04] + BoudRate=0x0000  DMAR=7  DMAW=0
[11:16:04] Crate service started.
[11:16:04] Rescan attached Crates...
[11:16:04] Found usb devices >> total=1  LTRCrates=1
[11:16:07] RST.XXXX module configuration updated. mconfig=00C2
[11:16:07] WST.XXXX send STOP+RESET+STOP to module. slot=2
[11:16:07] WST.XXXX send STOP+RESET+STOP to module. slot=7
[11:16:07] WST.XXXX send STOP+RESET+STOP to module. slot=8
[11:16:07] RST.XXXX found new module. slot=2  mid=2B2B (LTR43)
[11:16:07] RST.XXXX found new module. slot=8  mid=0B0B (LTR11)
[11:16:07] RST.XXXX found new module. slot=7  mid=2222 (LTR34)
[11:16:07] RST.XXXX change baud rate to 0x0040
[11:16:09] RST.XXXX module configuration updated. mconfig=00C3
[11:16:09] WST.XXXX send STOP+RESET+STOP to module. slot=1
[11:16:09] RST.XXXX found new module. slot=1  mid=2B2B (LTR43)
[11:16:40] Rescan attached Crates...
[11:16:40] Found usb devices >> total=1  LTRCrates=1
[11:16:41] Rescan attached Crates...
[11:16:41] Found usb devices >> total=2  LTRCrates=1
[11:16:41] Rescan attached Crates...
[11:16:41] Found usb devices >> total=2  LTRCrates=1
[11:16:41] Rescan attached Crates...
[11:16:41] Found usb devices >> total=2  LTRCrates=1
[11:16:41] Rescan attached Crates...
[11:16:41] Found usb devices >> total=2  LTRCrates=1
[11:16:41] Rescan attached Crates...
[11:16:41] Found usb devices >> total=2  LTRCrates=1
[11:16:41] Rescan attached Crates...
[11:16:41] Found usb devices >> total=2  LTRCrates=1
[11:16:42] Rescan attached Crates...
[11:16:42] Found usb devices >> total=2  LTRCrates=1
[11:16:42] Rescan attached Crates...
[11:16:42] Found usb devices >> total=2  LTRCrates=1
[11:16:42] Rescan attached Crates...
[11:16:42] Found usb devices >> total=2  LTRCrates=1
[11:16:42] Rescan attached Crates...
[11:16:42] Found usb devices >> total=2  LTRCrates=1

Похоже на сбои по USB. Клемму заземления крейта LTR соедините коротким проводом большого сечения с корпусом системного блока компьютера. Используйте основные USB-порты системного блока, а не дополнительные. Если эти меры не помогут, будем думать дальше...

Находиться-то он находится - судя по логу, происходила ошибка инициализации крейта.

Кстати, у Вас довольно древняя версия ltrserver. Если есть желание, можно поставить свежую из http://www.lcard.ru/download/ (необязательно вместо, можно параллельно со старой).
В частности, в новом сервере более понятно ведется протокол, уровень журнализации выбирается в меню (для отладки надо ставить максимальный - 7).

По основному вопросу актуален совет А.Гарманова.
Соединение земель в первую очередь. Что касается портов USB, то под основными портами понимаются разъемы, припаянные к материнской плате (т.е. задние) - дело в том, что на некоторых корпусах разъемы USB, выведенные на переднюю панель, бывают подключены неудачным кабелем. USB-хабы тоже бывают непредсказуемы.

Спасибо за ответы.

LTR-крейт объединен с системным блоком через общий провод заземления.
USB-порты используются запаянные на мат.плате.

А вот насчет версии сервера - попробуем новую. Результат сообщу.

Кстати, какая у Вас операционная система?

Еще интересно, какой чипсет USB (и есть ли возможность проверить с другим - например, поставить PCI-плату с контроллером USB). Хотя у LTR проблем аппаратной совместимости вроде бы не было.

Еще драйвер ldevusbu.sys можно попробовать обновить (DriverSetup.exe в том же архиве, где инсталлятор ltrserver).

"LTR-крейт объединен с системным блоком через общий провод заземления."
- Если объединен  через провод заземления сетевой вилки системного блока, то это правильно - это само собой. Но я о другом говорил. Для борьбы с наносекундными помехами, от которых иногда сбоит интерфейс USB, помогает непосредственная короткая связь проводом большого сечения между клеммой заземления крейта LTR и системного блока (под винт около его источника питания).

Кстати мне с ноутом помогло заземление через крепление разъёма внешнего монитора. А то иногда в UTR видел модули LTR255 в слота 4, 9, 11. И это на 8-местном крейте.

to nikkudr:
Где у ноутбука взять точку заземления - здесь универсальных советов нет, поскольку конструкции бывают разные. По идее нужна такая точка, которая наиболее близка к полигону земли материнской платы. Иногда вообще такой внешней точки подключения нет (или она неудобна для подключения), и в этом случае ноутбук можно поставить на металлическую пластину, на которую заземлить внешние USB-устройства (и саму эту пластину заземлить) - это сильно улучшит ЭМС (проверено).