DATEREMOTE CDS-9020, Manual

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Signals traveling along the cable are attenuated and distorted as they pass. Attenuation increases as the
length of the cable increases. This effect is largely due to the electrical capacitance of the cable.
The maximum load capacitance is specified as 2500pf (picofarad) by the standard. The capacitance of
one meter of cable is typically around 130pf, thus the maximum cable length is limited to around 17
meters. However, This is a nominal length defined by the standard, and it is possible to use longer cables
up to 30 meters, with low-capacitance cables, or with slow data rates and a proper error correction
mechanism.
•
Interface Mechanical Characteristics
The connection of the DCE and the DTE is done with a plug in connector. The female connector should be associated with
the DCE. The following table lists the pin assignments defined by the standard. The type of connector to be used is not
mentioned in the standard, but the DB-25 (or on IBM -AT's, a minimal DB-9) connectors are almost always used.
•
Pin designation for the 25-pin and 9-pin DB connector
includes equivalent CCITT V.24 identification, and signal direction
DB-25 DB-9 Common EIA
Pin # Pin # Name Name CCITT DTE-DCE Formal Name
----- ----- ----- ----- ----- ------- -------------------
1 FG AA 101 - Frame Ground
2 3 TD BA 103 ---> Transmitted Data, TxD
3 2 RD BB 104 <--- Received Data, RxD
4 7 RTS CA 105 ---> Request To Send
5 8 CTS CB 106 <--- Clear To Send
6 6 DSR CC 107 <--- Data Set Ready
7 5 SG AB 102 ---- Signal Ground, GND
8 1 DCD CF 109 <--- Data Carrier Detect
9 NOT USED
•
Diagram of the DB-25 and DB-9 connectors
male connectors , front view
1 13 1 5
_______________________________ _______________
\ . . . . . . . . . . . . . / \ . . . . . /
\ . . . . . . . . . . . . / \ . . . . /
--------------------------- -----------
14 25 6 9
TROUBLE SHOOTING
If the signal is weak, will data transmission slow down?
Generally, the speed at which data moves is not affected by signal strength. However, there may be