Cermetek Microelectronics, Inc.
High Speed Modem and FAX Family
2003 Cermetek Microelectronics, Inc.
Page 7
Document No. 607-0003 Revision K3 (09/03)
code 0) or the command is valid or accepted, or with
an ERROR (result code 4) if the command is not
recognized. The detail contained in the error result
codes signaled to the DTE depends on the level of
message suppression employed by the user. As can
be seen from Tables 5A, 5B and 5C, specifying X4
allows the HS Modem to utilize the entire range of
non-extended messages, whereas X0 suppresses all
but the very basic result codes. Most of the result
codes allowed under X1, X2 and X3 are considered
call progress status codes and, in practice, are
suppressed except for the case of debugging
activities. It is recommended that the non-extended
result codes be used in all cases.
It should be noted that the default connect result codes
9-20 indicate DTE connection speed, not Carrier Line
DCE speed. Hence, a CH1794 will connect at a
maximum speed of 19.2kbps (result code 16). The
CH1799 will connect at a maximum DTE speed of
38.4kbps (result code of 17) and the CH2056 will
connect at a maximum speed of 57.6kbps (result code
18) unless the DTE is forced to a higher speed by
selection of data compression. In this case, the
maximum DTE to modem speed is 230.4kbps (result
code20).
Extensions to the basic result code set may be
specified by Register S95, which allows for the use of
result codes 40-64, 165-194.
IMPORTANT NOTE
Result codes 53-64 are supported by the CH1799
and CH2056. Result codes 165-194 are only
supported by the CH2056. To obtain a detailed
status report for a given modem communication
configuration, use the
AT\V1
command. Executing
this command at setup will cause the modem to
connect and return a message on line consisting of
<DTE speed> <modulation> <error protocol> <line
speed of connection>.
LEASED LINE OPTION
The CH1799LL is a leased line version of the CH1799.
Whereas the CH1799 requires an active voltage
bearing or wet PSTN line for normal operations
(typically, 48VDC on-hook line voltage), the CH1799LL
is designed to operate over a non-voltage bearing or
dry line.
The CH1799LL will only operate properly on a dry line.
Damage will occur if used on a wet line. The
CH1799LL does not support ring detect but does
support off-hook control. Refer to Cermetek
Application Note # 116 for examples and instructions
to establish a connection over a leased dry line wire
pair. Note that the length of the leased line is limited
to 20,000 feet. Use PSTN line protection as
recommended in Figure 6B and in Cermetek
Application Note # 126. Follow all applicable
requirements for FCC Part 68 compliance. The User
is responsible to ensure that FCC Part 68 compliance
is maintained.
As an alternative, the CH1799 will operate on a leased
line if the line is made wet by application of a DC
voltage. Refer to Cermetek Application Note # 114
.
WARNING
Operation of the CH1799LL on a standard PSTN
line will damage the CH1799LL and void its
warranty. Further, operation of the CH1799LL on a
dry line without using proper current limiting circuitry
as outlined in Cermetek Application Note # 126 may
cause damage to the CH1799LL and will also void
its warranty.
Table 4. Pin Comparison of CH1786 and HS
Modem Family.
PIN
CH1786
HS Modem Family
1 RING
RING
2 TIP
TIP
3 RXA
T1
4 TXA
NC
5 SPK
SPK
6 NC
NC
7 NC
NC
8 SLEEP
OPEN*
9 NC
NC
10 TXD
TXD
11
RXD
RXD
12
V/D
OPEN*
13 DTR
DTR
14
DST
DSR
15
RI RI
16
CTS (FX only)
CTS
17 DCD
DCD
18 HS
NC*
19 V
CC
V
CC
20 GND
GND
21 RST
RST
22 NC
RTS
NOTES:
1. * Indicates a difference between the CH1786 and
the HS Modem. The HS Modem may be directly
substituted for the CH1786 except in applications
where pins 8, 12, or 18 are used.
2. NC signifies ‘No Connect.’
3. Effective 31 March 2000, the HS Modem will no
longer support the HS indication function.
Therefore, pin 18 should be a ‘No Connect’ in all
applications.
