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CHAPTER 9: TECHNICAL INFORMATION
7500 — Asynchronous DCE
Attached Data Terminal Equipment Requirements
The 7500 requires attached data terminal equipment communicating via asynchronous 10-bit
transmission including parity bit, 1 start bit, and at least 1 stop bit. For local mode operation and data
call control, the character code set must be ASCII.
Data Rates
The 7500 operates at asynchronous full-duplex rates of 300, 1200, 2400, 4800, 9600, and 19200 bps.
DCE EIA Interface Information
The 7500 provides a female EIA-232D receptacle. Where this product employs the EIA-232D
standard interface, older equipment which adheres to the RS-232C standard can also be connected. The
EIA customer interface pin assignments are listed in the table below.
Asynchronous DCE Pin Assignments
Table N:
Pin 2 - Transmitted Data (BA)
The data from the attached terminal must have one start bit, eight information bits, and at least one
stop bit. The 7500 generally ignore parity in Local Mode and transports it transparently in Data Mode.
(The exceptions are: 1) the 7500 is always sensitive to the parity of the xon/xoff characters; and 2) the
7500 always ignores the parity of the Attention sequence characters and the Forwarding characters.)
The 7500 supports only ASCII-formatted data in the Local Mode. The 7500 recognizes a break signal
as a SPACE received for at least 1 character time plus 20 msec. The setting of the Break option governs
the 7500's response to the break signal in Data Mode.
CIRCUIT
PIN
NO.
MNEMONIC
2
BA
BB
3
4
CA
5
CB
6
CC
AB
7
8
CF
—
9
—
10
L L
18
CD
20
21
RL
22
CE
25
TM
DESCRIPTION
Transmitted Data
Received Data
Request to Send
Clear to Send
Data Set Ready
Signal Ground
Received Line Signal Detect
Test +V
Test -V
Local Loopback
Data Terminal Ready
Remote Loopback
Ring Indicator
Test Mode
129
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