Bell standard 201 modems
UDS 201BC/AS Modem

UDS 201 BC/AS Modems are reliable 2,400bps transmission compatible with Bell 201B and 201C 
Synchronous Asynchronous modems in the  Multi-Point / Multi-Drop, Dial, 2 or 4 wire lease line mode.

We stock UDS 201BC/AS modems in refurbished and used

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201 SERIES 2400 bps modems
UDS 201C/D modem
UDS 201BC/AS modem

UDS 201BC-AS pic.gif (12780 bytes)


201 SERIES 2400 bps modem

UDS 201 series modems operate at 2400 bps and are Bell compatible. Internal diagnostic features allow the user to isolate communications faults to the modem, telephone line or data terminal equipment.


* 201BC/AS modem Operates over 2-wire dial-up or 4-wire leased lines; Provides synchronous or asynchronous operation

* 201C/D modem Includes serial synchronous auto dialer which utilizes bisync protocol for DTE dialing

* 2140 Multi-protocol dialer/modem providing 2400 bps operation compliant with CCITT V.26 bis and Bell 201C; Auto dialing capabilities include V.25 bis, bisync, and SDLC, as well as 801 mode; Handles numbers up to 36 digits long - tone or pulse dial type; Options may be added via straps and switches, or can be software selected


UDS 201C/D modems
UDS 201BC/AS modems

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The 201 BC/AS modem is a 2400 bps per second modem designed far Synchronous or Asynchronous data communications. The unit combines two modem types;

    201B modem for leased line operation - 2 or 4 wire
    201C modem for operation of the Pubic Switched Telephone Network (PSTN)

This combination and the addition of local and remote diagnostic tests provide flexibility in designing communication networks using any synchronous or asynchronous data protocol at 2400 bps, The 20IBC/AS is available in either a 115 VAC or a 230 VAC powered version. When used as a 201A in leased line operation. data is transferred in half-duplex mode on 2-Wire and in full-duplex mode on 4 wire lines. Switched line operation in 201C mode is always half-duplex.

Numerous options are provided so the UDS 201BC/AS modems may be tailored to your particular application. These options are set by straps and switches on the modem printed circuit board Control of local and remote diagnostic tests is provided by a rotary switch on the front panel. Modem operations monitored by observing the nine LED indicators on the front panel. The printed circuit board containing the RM16M 20IBC/AS modem card also fits in the UDS RM-16 shelf.

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for the UDS 201BC/AS modems

Data Rate: 2400 bits per second synchronous
Character Format: Synchronous. or 8,9,10, of I I bit asynchronous
Communications Mode: Over PSTN 2-wire, half-duplex over Leased Lines; 2-wire, half-duplex, at 4-wire, full duplex
Modulation: Differentially Phase Shift Keyed (DPSK)
Carrier Frequency: 1800 Hz±0.01%
Receiver Sensitivity: -45 dBm or -30 dBrm selectable
Telephone Line Interface: 600 ohms transformer coupled, transient protected
Line Connection: Over PSTN: Permissive or programmable
Over Leased Lines; Transmit levels selectable for 0 to -12 d8m
Line Conditioning: Telephone line conditioning is not required
Digital Interface: EIA RS-232C and CCITT V.24
Automatic Answer: Over PSTN: optional automatic or manual answering
Originate: Over PSTN: manual using exclusion key telephone
Dimensions: 7"W x 2.25"H x 9.60"D: Weight is approximately 2 lb, 9 oz.
Temperature: Operating: 0 to +50C Storage. -40 to +85C
Humidity: 96% relative, non-condensing
Power Requirements: 115Vac±10%; 50/60 Hz or 230Vac±10%
50/60 Hz for applicable models.
47 to 63hz
10 Watts maximum

Fax 301-924-7403

3405 Olandwood Court
Olney, MD 20832