ZyXEL U-90E User Guide - Page 48

Default Modem Settings for PC’s, Table 4-6 Default Settings

Get ZyXEL U-90E PDF manuals and user guides View all ZyXEL U-90E manuals
Add to My Manuals
Save this manual to your list of manuals

Page 48 highlights

U-90E Data/Fax Modem The serial port is driven by interrupts. Every interrupt needs a certain amount of overhead processing time. Too many interrupts reduce the computer's efficiency. The UART 16450 is very commonly used in serial port devices. For every character (byte) received, it generates an interrupt. If your hardware allows it and if your software supports it, replace the 16450 UART with a 16550 model. This newer chip has an internal buffer and generates an interrupt for up to every 16 characters (several trigger levels are available). With this UART installed, you may drive your serial port at 57600 bps and above. While data is written from the transfer-buffer to your hard-disk, characters may be lost at the serial port. This is due to the fact that disk-access interrupts have a higher priority than serial port interrupts. If you are running at a high serial speed, e.g. 230.4Kbps or 460.8Kbps, on your PC, be sure to enable the disk cache by including SMARTDRV execution in your AUTOEXEC batch file. 4.5.1 Default Modem Settings for PC's The U-90E factory settings are configured for operation with PC type computers and communication software. In most cases, no additional settings will be required. The following are some of the default settings that are used for operation with PC computers and software: AT Command E1 &C1 &D2 &K4 &N0 Description Echoes command characters. Carrier detect follows remote carrier. Modem disconnects on DTR on-to-off transition. Uses both V.42 and MNP 4 error correction, and V.42bis and MNP 5 data compression. Modem negotiates highest possible connection speed. Table 4-6 Default Settings 4-10 Basic Modem Operation

  • 1
  • 2
  • 3
  • 4
  • 5
  • 6
  • 7
  • 8
  • 9
  • 10
  • 11
  • 12
  • 13
  • 14
  • 15
  • 16
  • 17
  • 18
  • 19
  • 20
  • 21
  • 22
  • 23
  • 24
  • 25
  • 26
  • 27
  • 28
  • 29
  • 30
  • 31
  • 32
  • 33
  • 34
  • 35
  • 36
  • 37
  • 38
  • 39
  • 40
  • 41
  • 42
  • 43
  • 44
  • 45
  • 46
  • 47
  • 48
  • 49
  • 50
  • 51
  • 52
  • 53
  • 54
  • 55
  • 56
  • 57
  • 58
  • 59
  • 60
  • 61
  • 62
  • 63
  • 64
  • 65
  • 66
  • 67
  • 68
  • 69
  • 70
  • 71
  • 72
  • 73
  • 74
  • 75
  • 76
  • 77
  • 78
  • 79
  • 80
  • 81
  • 82
  • 83
  • 84
  • 85
  • 86
  • 87
  • 88
  • 89
  • 90
  • 91
  • 92
  • 93
  • 94
  • 95
  • 96
  • 97
  • 98
  • 99
  • 100
  • 101
  • 102
  • 103
  • 104
  • 105
  • 106
  • 107
  • 108
  • 109
  • 110
  • 111
  • 112
  • 113
  • 114
  • 115
  • 116
  • 117
  • 118
  • 119
  • 120
  • 121
  • 122
  • 123
  • 124
  • 125
  • 126
  • 127
  • 128
  • 129
  • 130
  • 131
  • 132
  • 133
  • 134
  • 135
  • 136
  • 137
  • 138
  • 139
  • 140
  • 141
  • 142
  • 143
  • 144
  • 145
  • 146
  • 147
  • 148
  • 149
  • 150
U-90E Data/Fax Modem
The serial port is driven by interrupts. Every interrupt needs a certain amount of overhead
processing time. Too many interrupts reduce the computer's efficiency. The UART 16450 is very
commonly used in serial port devices. For every character (byte) received, it generates an interrupt.
If your hardware allows it and if your software supports it, replace the 16450 UART with a 16550
model. This newer chip has an internal buffer and generates an interrupt for up to every 16
characters (several trigger levels are available). With this UART installed, you may drive your
serial port at 57600 bps and above.
While data is written from the transfer-buffer to your hard-disk, characters may be lost at the serial
port. This is due to the fact that disk-access interrupts have a higher priority than serial port
interrupts. If you are running at a high serial speed, e.g. 230.4Kbps or 460.8Kbps, on your PC, be
sure to enable the disk cache by including SMARTDRV execution in your AUTOEXEC batch file.
4.5.1 Default Modem Settings for PC
’
s
The U-90E factory settings are configured for operation with PC type computers and
communication software. In most cases, no additional settings will be required. The following are
some of the default settings that are used for operation with PC computers and software:
AT Command
Description
E1
Echoes command characters.
&C1
Carrier detect follows remote carrier.
&D2
Modem disconnects on DTR on-to-off transition.
&K4
Uses both V.42 and MNP 4 error correction, and V.42bis
and MNP 5 data compression.
&N0
Modem negotiates highest possible connection speed.
Table 4-6 Default Settings
Basic Modem Operation
4-10