Page 28 of 80
Equipment description
553-2731-100
Standard 5.00
April 2000
Table 2
ADM user option selectors (Part 1 of 3)
Selector
Description
Speed setting knob (S2)
A 16-position switch used to select transmission speed (bits
per second) of a data call (Notes 3 and 4).
Option switches (S3)
The eight switches allow selection of data code options and
operating modes that match the receive and transmit
characteristics of the receiving data terminal.
Asynchronous ADM Operation
The asynchronous ADM has an 8-bit transmitter/receiver. To
handle all of the combinations of codes it might receive or
need to transmit, which might be less or greater than 8 bits,
the ENH-INH and EVEN-ODD switches allow it to add or
delete bits to make the code always equal 8 bits. Most
devices today use the 8-bit code, so the INH and 8 CODE
switches are normally operated. When INH is operated, the
EVEN-ODD switch setting is ignored.
ENH—INH
ENH allows the parity check; this allows the addition of a
non-information bit to the data, making the number of ones
in a grouping of binary bits always even or odd. INH prevents
the addition of the parity bit.
EVEN—ODD
This determines the parity check type, EVEN, when the
number of binary ones in a data word is always maintained
as an even number or ODD, when the number of ones in the
data word is odd.
HDX—FDX
Provides for the transmission aspects: HDX when
half-duplex direction of transmission is under dynamic
control of EIA leads CTS, RTS, and CD (this switch provides
local carrier monitoring of local request-to-send to ensure
compatibility with 2-wire modem); FDX when full-duplex
communications is required.
7—8 CODE
Transmission codes use different character lengths and
different start/stop bit configurations. This switch and the
selection switch (S4) provide for 5 through 8 character codes
(Note 1).
1—2 STOP
This switch and selection switch (S4) provide the correct
stop bits to match the required code configuration (Noteþ1).
