|The SRM-9, Async/Sync Short Range
Modem, is used for local data distribution, connecting full or half
duplex Sync/Async DTEs to other DTEs over unconditioned 4-wire / 2-wire
lines. SRM-9 operates at data rates of 32 to 128 kbps in Sync mode and
9.6 to 115.2 kbps in Async mode, at distances up to 16.5 km (10 miles),
depending on wire gauge and data rate.
- Four models are available:
- SRM-9/V.24, with V.24/UP interface (unpowered)
- SRM-9/V.24, with V.24 interface (powered)
- SRM-9/V.35, with V.35 interface
- SRM-9/X.21, with X.21 interface
- SRM-9/530, with RS-530 interface
Each model has a 25-pin D-type connector for the
DTE interface. V.35 interface: a 45 cm cable, with a 25-pin, male
connector on one side and a 34-pin, male or female connector on the
other side, is supplied.X.21 interface: a 45 cm cable, with a 25-pin
male connector on one side, and a 15-pin X.21, female connector on the
other side, is supplied.
- SRM-9 performs diagnostic loops in compliance
with ITU V.54 standard. Two V.54 loops are available: analog loop
(V.54 Loop 3) and remote digital loop(V.54 Loop 2). These loops are
activated either by a dip-switch or by the DTE interface Circuit 141
(Pin 18) and Circuit 140 (Pin 21). (Loopbacks in SRM-9/X.21 are
activated by dipswitch only.) A proprietary local digital loop is
available and can be activated only by the modem's switches. This loop
connects the local RD to the TD. A TEST LED lights when any diagnostic
loop is ON.
- SRM-9 includes a built-in BERT according to the
V.52 standard for testing link communication. The internal BERT is
activated by the dip-switch (PATT). The BERT checks the received data,
and the error LED (ERR) lights when errors are detected.
- Asynchronous transmission is provided by
internal conversion from Async to Sync in compliance with the ITU V.22
bis standard. Different Async formats are switch selectable.
- In Synchronous mode, transmit timing can be
provided by three alternative sources:
- Loopback clock derived from the receive signal.
- The modem's carrier can be set for either
continuous operation (point-to-point application) or controlled
operation by the RTS signal (multipoint application or passing control
- The low transmit level minimizes crosstalk on
adjacent circuits within the same cable. Data is transmitted and
received at a balanced impedance, ensuring high immunity to circuit
noise. Additionally,SRM-9 is coupled to the line through isolation
transformers, which protect against AC or DC overvoltages.
- SRM-9/V.24/UP/RS-232 interface can operate
without a power supply, using ultra-low power from the standard
V.24/RS-232 data and control signals. When the DTE cannot provide the
power required, SRM-9's power consumption can be significantly reduced
by disabling the LEDs (setting via dip-switch).
- Six LED indicators are available to facilitate
diagnostics: TST, DCD, TD, RTS, RD, ERR.
- The line interface is a 5-screw clip terminal
block or an RJ-45 connector.
- Synchronous or Asynchronous
- Data rates up to 128 kbps Sync and 115.2 kbps Async
- V.54 diagnostics, including local and remote
- Built-in BER tester in compliance with V.52
- Full or half duplex for point-to-point or
- Half duplex over 2-wire lines
- Internal, external or receive clock
- Controlled or continuous carrier
- V.35, V.24 / RS-232, X.21 or RS-530 interfaces
- Isolation transformers
- Operates with an external, wall-mounted power
- No AC power required (only for SRM-9/V.24/UP)
- LED indicators
Synchronous/Asynchronous Short Range Modem
Sync/ Async Unpowered Short Range Modem
||Specify DTE interface:
V24 for V.24 interface, female connector
V35 for V.35 interface, female connector
X21 for X.21 interface, female connector
530 for RS-530 interface, female connector
||Specify line interface:
RJ45 for RJ-45 jack
(Default is Terminal Block)
PS-230/9/300 wall-mounted 9 VDC/230 VAC, 300 mA power supply
PS-115/9/300 wall-mounted 9 VDC/115 VAC, 300 mA power supply