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Four wire mode allows full duplex data transfers. RS 485 does not define a connector pin out or a set of
modem control signals. RS 485 does not define a physical connector.
RS-530/530A
RS 530 (a.k.a. EIA 530) compatibility means that RS 422 signal levels are met, and the pin out for the DB 25
connector is specified. The EIA (Electronic Industry Association) created the RS 530 specification to detail
the pin out and define a full set of modem control signals that can be used for regulating flow control and
line status. The major difference between RS-530 and RS-530A lies in some of the modem control interface
signals. In RS-530 the signals all of the modem control signals are differential, in RS-530A some of these
signals are single ended. The RS 530 specification defines two types of interface circuits, Data Terminal
Equipment (DTE) and Data Circuit-Terminating Equipment (DCE). The Sealevel Systems adapter is a DTE
interface.
V.35
V.35 is a standard defined by ITU (formerly CCITT) that specifies an electrical, mechanical, and physical
interface that is used extensively by high-speed digital carriers such as AT&T Dataphone Digital Service
(DDS). ITU V.35 is an international standard that is often referred to as Data Transmission at 48 Kbps using
60 - 108 KHz Group-Band Circuits. ITU V.35 electrical characteristics are a combination of unbalanced
voltage and balanced current mode signals. Data and clock signals are balanced current mode circuits.
These circuits typically have voltage levels from 0.5 Volts to -0.5 Volts (1 Volt differential). The modem
control signals are unbalanced signals and are compatible with RS-232. The physical connector is a 34 pin
connector that supports 24 data, clock, and control signals. The physical connector is defined in the ISO-
2593 standard. ITU V.35 specification defines two types of interface circuits, Data Terminal Equipment
(DTE) and Data Circuit-Terminating Equipment (DCE). The Sealevel Systems adapter is a DTE interface.
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© Sealevel Systems, Inc.
5104e & 5104es Manual | SL9273 8/2021
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