RAD DATA COMMUNICATIONS
MTM-20 (X.21, DC POWER)
Card Type | Modem (synchronous) |
Chipset | Unidentified |
Transfer Rate | 32/64Kbps |
Data Modulation | QAM |
Data Bus | Serial |
CONNECTIONS | |||
Function | Label | Function | Label |
DC power in | CN1 | Analog loopback test switch | SW2 |
X.21 serial port | CN2 | Remote digital loopback test switch | SW3 |
Line out (see pinout below) | SC1 | Test pattern switch | SW4 |
Local digital loopback test switch | SW1 | ||
Note:Modem can be made to perform self-test by holding down SW2 and SW4. The DCD, TEST, and SQ LEDs should go on, and the RD LED should go off. |
SC1 PINOUT | |||
Function | Terminal | Function | Terminal |
Ground | 1 | Not used | 5 |
Not used | 2 | Transmit line | 6 |
Receive line | 3 | Transmit line | 7 |
Receive line | 4 |
USER CONFIGURABLE SETTINGS | |||
Setting | Label | Position | |
» | DCD forced high | JP3 | Pins 3 & 4 closed |
DCD normal | JP3 | Pins 1 & 2 closed | |
» | Signal ground connected to chassis ground | JP4 | Pins 1 & 2 closed |
Signal ground not connected to chassis ground | JP4 | Pins 2 & 3 closed | |
» | Line speed set to 64Kbps | SW5 | Position 4 |
Line speed set to 32Kbps | SW5 | Position 3 |
TRANSMIT LEVEL | ||||||
Setting | JP5/A | JP5/B | JP5/C | JP5/D | JP5/E | |
» | 0dBm | Closed | Open | Open | Open | Open |
-3dBm | Open | Closed | Open | Open | Open | |
-6dBm | Open | Open | Closed | Open | Open | |
-9dBm | Open | Open | Open | Closed | Open | |
-12dBm | Open | Open | Open | Open | Closed |
CLOCK SOURCE | ||
Setting | JP1 | |
» | Internal | Pins 1 & 2 closed |
External | Pins 3 & 4 closed | |
Received | Pins 5 & 6 closed |
LINE LENGTH | ||
Setting | JP2 | |
» | 0-10Km | Pins 3 & 4 closed |
7-13Km | Pins 1 & 2 closed | |
Auto select (not yet implemented) | Pins 5 & 6 closed |
DIAGNOSTIC LED(S) | |||
LED | Color | Status | Condition |
PWR | Green | On | Power is on |
PWR | Green | Off | Power is off |
RTS | Yellow | On | RTS signal is high |
RTS | Yellow | Off | RTS signal is low |
TD | Yellow | On | DSU is transmitting SPACE |
TD | Yellow | Off | DSU is not transmitting |
TD | Yellow | Blinking | DSU is transmitting data |
RD | Yellow | On | DSU is receiving SPACE |
RD | Yellow | Off | DSU is not receiving |
RD | Yellow | Blinking | DSU is receiving data |
DCD | Yellow | On | Carrier signal detected |
DCD | Yellow | Off | Carrier signal not detected |
TEST | Red | On | DSU is in test mode |
TEST | Red | Off | DSU is not in test mode |
SQ | Yellow | On | Signal quality is good |
SQ | Yellow | Blinking | Signal quality is poor or test pattern contains errors |