|The SRM-8H, High Speed
Short Range Modem, is used for local data distribution,
connecting full duplex Sync or Async DTEs, computers or
controllers over unconditioned 4-wire dedicated lines.
SRM-8H operates at data rates of 56 or 64 kbps, at distances
up to 10 km (6 miles), according to the wire gauge and data
- Four models are available:
- SRM-8H/V.24, with V.24/RS-232
- SRM-8H/V.35, with V.35 interface
- SRM-8H/X.21, with X.21 interface
- SRM-8H/530, with RS-530
Each model has a 25-pin D-type
connector for the DTE interface. V.35 interface: a 45 cm
(17.7") cable is supplied, with a 25-pin, female connector
on one side and a 34-pin, male or female connector on the
other side.X.21 interface: a 45 cm (17.7") cable is
supplied, with a 25-pin male connector on one side, and a
15-pin X.21, male or female connector on the other side.
- Four LED indicators are available
to facilitate diagnostics: Power, Test, Data Carrier
Detect and Transmit Data.
- Transmit timing is provided via
three sources: an internal oscillator, an external clock
or a loopback clock derived from the receive signal. For
the X.21 interface, transmit timing can be either via
internal clock or recovered from the line.
- The modem's carrier is
strap-selectable for either continuous operation, or
switched operation for passing control signals end-to-end.
Switched operation is controlled by the RTS signal.
- SRM-8H performs diagnostic loops in
compliance with the ITU V.54 standard. Two V.54 loops are
available: local analog loop (V.54, loop 3) and remote
digital loop (V.54, loop 2). The loops are activated by a
3-position switch in all models, or by the DTE interface
Circuit 141 (Pin 18) and Circuit 140 (Pin 21) in all
models except SRM-8H/X.21. The Test LED lights when any
diagnostic loop is active.
- The low transmit level minimizes
crosstalk onto adjacent circuits within the same cable.
Data is transmitted and received using a balanced
interface, ensuring high immunity to circuit noise.
Additionally, SRM-8H is coupled to the dedicated line
through isolation transformers which, in conjunction with
other circuitry, protect against AC or DC overvoltages.
- The line interface consists of two
independent connectors: a 5-screw terminal block, and a
selectable RJ-11 or RJ-45 connector (see Ordering).
- Power is supplied from a standard,
wall-mounted power supply, 300 mA (center - positive;
sleeve - negative).
- SRM-8H is also available as a card
for mounting in a 19" modem rack (see
CMN-16 card, CMN-C8H data sheet
- Synchronous or Asynchronous
- Data rates of 56 or 64 kbps, selectable
- V.54 diagnostics, including local and remote test
- Internal, external or receive clock
- Transmission range up to 10 km (6 miles)
- Controlled or continuous carrier
- Isolation transformers
- V.35, V.24/RS-232, X.21 or RS-530 interfaces
- LED indicators
- Miniature, lightweight, easy to install
- Operates with an external, wall-mounted power
High Speed Short Range Modem
V24 for V.24 interface
V35M for V.35 interface, male connector
V35F for V.35 interface, female connector
X21M for X.21 interface, male connector
X21F for X.21 interface, female connector
530 for RS-530 interface
||Specify line connector:
RJ11 for RJ-11 jack
RJ45 for RJ-45 jack
(Terminal block provided with all models)
Wall-mounted 9 VDC / 230 VAC power supply
Wall-mounted 9 VDC / 115 VAC power supply
For ordering information on the card version for the CMN-16 rack, see the