The MIU202T is an industrial grade Bell202T modem for connection to
unconditioned and conditioned, voice grade, type 3002 two or four-wire leased
lines and metallic lines (eg; pilot wires). It can be powered from a wide range of
AC and DC power supplies, it is internally surge protected on both the power
and analog lines, and it will operate in temperatures from -40 to +85 deg C.
Internally, the MIU202T consists of a baseboard and a communication module. The baseboard includes the power supply regulation and surge
protection. The communica tion module is a Telenetics™ Pony Express™
PE202T Modem Module.
The MIU202T is packaged specifically for the harsh environments found in
utility substations and industrial facilities. Though functionally similar to
commercial modems, the MIU202T includes special features that make it
particularly well suited for utility and industrial applications:
Environment:The MIU202T has been designed specifically for use in
harsh environments. In addition to an extended temperature
range (-40 to +85º C), the MIU202T includes surge, shock,
vibration, and safety features superior to those of
conventional commercial modems.
Power Supply:The MIU202T can be powered from a broad range of AC
and DC power supplies, such as an auxiliary supply (eg;
12VDC) from another piece of equipment, 125VDC from a
station battery or a standard 120VAC.
Industrial: The MIU is packaged in a rugged, compact, non-metallic
(ABS) enclosure. Designed for unmanned locations, the
MIUs do not include the array of pushbuttons and LEDs
normally associated with consumer-type modems.
Configuration is by dip switches. Standard industrial
connectors for data, analog and power interfaces allow
reliable interconnection to other industrial components.
Receiver Equalization: Compromise Equalization
Self Test Diagnostics: None
Local Analog Loopback: See Section 13
Local Digital Loopback: See Section 13
Remote Analog Loopback See Section 13
Remote Digital Loopback See Section 13
Anti-Streaming: OFF or 45 Seconds (+ 5 sec) *
RTS/CTS delay: 1ms, 12ms, 35ms or 50ms (+5%) *
Note: Soft Carrier will effect RTS/CTS
delay time (see Dip Switch Settings ~
Section 8) Constant Carrier Switch Selectable ON or OFF
Soft Carrier Turn Off 20ms of 900Hz after RTS is turned
The MIU202T contains analog circuitry for connection to the public conditioned or
unconditioned, Bell type 3002, 2 or 4-wire, full duplex voice grade leased lines or
metallic lines (eg; pilot wires). The MIU202T will also interface to Power Line
Carrier or Microwave radio voice channel networks.
The MIU202T has an RJ-11terminated connector. The following lists the
MIU202T analog interfaces
Analog Line Type:
Conditioned or unconditioned, Bell type 3002, 2 or 4-wire, full duplex voice grade or
metallic lines or better.
Analog Line Specifications:
Bandwidth 300 Hz to 3400 Hz (±3dB)
Impedance 600 / 900 ohms , balanced
Frequency Response 400 to 3000Hz (±2dB)
Receiver Input Level -16dBm max.
Output Level +7 dBm
Noise Signal Level -48 dBmO
The following table provides the Dip Switch settings required for most modem
application configurations:
Dip Switch Setting 1 2 3 4 5 6 7 8 9
4-Wire
Point-to-Point
4-Wire
Multi-Point
Master
4-Wire
Multi-Point
Slave
Rx Term. OFF
4-Wire
Multi-Point
Slave
Rx Term. ON
2-Wire
Point-to-Point
2-Wire
Multi-Point
Master
Line Term. ON
2-Wire
Multi-Point
Slave
Line Term. ON
2-Wire
Multi-Point
Slave
Line Term. OFF
The following pages provide hardware techniques for diagnosing communication
problems and thereby isolating the problem at the local modem, the remote
modem or the interconnecting line.
(a) LOCAL ANALOG LOOPBACK (Figure 2)
Requires a loop back cable with a built -in circuit for line loss to simulate a
typical leased line condition (See Figure 3).
Connect the loop back cable to the RJ11 connector on the modem under test.
Set Dip Switches as follows…
Switch 7 = OFF 4-Wire
Switch 9 = ON Soft Carrier Turn Off Enabled
Switch 1 = ON Transmit (TxA) Signal Level = 0dBm
Switch 3 = ON Receive (RxA) Signal Level = –33dBm
Switch 6 = OFF Switched Carrier
Switch 4&5 = ON RTS/CTS Delay = 50ms
Test 1: RTS/CTS Analog Control
Set RTS “ON” and check that CD (Carrier Detect) turns “ON”.
Turn RTS “OFF” and ensure that CD turns “OFF”
With RTS “ON”, run a test message at TxD and verify that the
same message is received at RxD with no data errors.
Test 2: Transmit Signal Power & Receive Levels
Set Dip Switch 1 OFF (TxA = -10dBm)
CD will be OFF.
Change Dip Switch 1 to ON (TxA = 0dBm)
CD should now be ON.