Installation
19
User’s Manual - DSP19.2 Fast Poll Modem
Configuring the Jumper Blocks
For Stand-alone Units
Jumper block JP1 is use to select RS-232/V24 or RS-485 interface with your DTE or RTU.
•
RS-232: Two shorting jumpers are placed over pins 1 & 3, and 2 & 4 (
default
)
•
RS-485: Place two shorting jumpers over pins 3 & 5, and 4 & 6
Jumper block JP3 is used to set the modem’s receiver termination impedance
•
600 ohms: A shorting jumper is placed over pins 2 & 3 (
default
)
•
High impedance: Place a shorting jumper over pins 1 & 2
For Rack-Mount Plug-in Modules
Jumper block JP1 is used to set the modem’s receiver termination impedance
•
600 ohms: A shorting jumper is placed over pin 2 & 3 (default)
•
High impedance: A shorting jumper is placed over pin 1 & 2
Select high receiver impedance (Hi-Z) if multiple modems are connected in a multi-
point configuration but without an impedance matching bridged such as private
metallic circuit environment. In this configuration, only one receiver should be
configured for 600 ohms.
Connecting to a Transmission Line
The modem has a transmission line interface that can be configured for 2- or 4-wire analog
connection, where one pair (Tx-A and Tx-B) is used to transmit data and the other pair (Rx-A
and Rx-B) is used to receive data. The transmit pair and receive pair are non-polarized.
Table 2-4 shows the pin numbers and corresponding signals for the modem. Figure 2-6
shows the transmission line interface.
NOTE:
For communication to occur, the Rx line of one modem must connect to the Tx
line of the other modem. The modem’s Tx/Rx pair are non-polarized.
NOTE:
The modem does not support leased-line operation with DC shielding current.
Leased-line connector pin assignments for the rack-mount module can be
found in the documentation for your Motorola/UDS RM16M.
