Dataplex DPX-213, User Manual

Page: 53 / 93

Section 5
APPLICATIONS
Copyright (C) Dataplex Pty Ltd
5-5
5.6 Extended Character Formats
Both MNP and AT protocols specify ten bit characters made up of one start bit, eight data
bits and one stop bit. The data bits may be seven data bits and one parity bit or eight data
bits with no parity bit. The V.22bis standard allows for character lengths from eight to
eleven bits including start and stop bits. The DPX-213 supports 8 to 11 bit characters
through the use of register S30. The Constant Speed Interface (CSI) and MNP /V42
features only support ten bit characters. Whenever eight, nine or eleven bit character
support is required, MNP and CSI must be turned off.
To operate with character lengths other than ten bits, the DPX-213 must be initially
configured with a 10 bit ASCII terminal, S30 needs to be set for the appropriate character
length, and then the modem will switch to the extended character format at the time a
connection is made. The 'pause'
+++
'pause' escape sequence must also be entered in
ten bit format.
The following command string is an example of the use of this facility.
AT&M1 S30=182 N0 &Z 1234567.
This sets the modem up to dial 1234567 when DTR is raised and then pass eleven bit
characters once the connection is established.
NOTE: See S30 settings in Appendix B to ensure that other bits are not corrupted
unnecessarily (MNP/CSI is disabled by setting S30 bits 0,1,2 to 0).
5.7 PABX Operating Problems
The modem needs only two wires connected to the exchange to operate, tip and ring.
These are connected to Pins 2 and 6 of the Telecom 605 plug as shown in Figure 5.1.
Business PABX and other handsets such as Telecom Commander systems often have extra
facilities on the handsets and non-standard wiring.
Using a modem on these circuits could cause unexpected results and possibly damage.
PABX makers follow their own design and wiring practices and it is unlikely one universal
cable will ever suit all applications. If any troubles are experienced with obtaining dial
tone, dialling out or receiving calls with the DPX-213, remove all extra wires from the
cable, leaving only Pins 2 and 6 active, and try again. If problems still persist contact your
PABX supplier for connection information.
Figure 5.1 Telecom 604 Plug