Specifications

44 Rockwell Automation Publication AG-SG001G-EN-P - April 2015
Chapter 3 Choosing Data Communication Equipment
Consult the vendor for information about their product offerings.
Analog Leased-line Modems
Depending on the speed of the modem you choose, you may need a better
conditioned line. A leased-line modem's cost is composed of two principal items:
• Monthly leased-line charges, which are directly proportional to the
conditioning or communication rate capability of the leased line
• Modem price, which is directly proportional to the modem's
communication rate capability
Therefore, the most efficient system matches the maximum communication rate
of the modem to that of the leased line to which the modems are attached.
For Point-to point, Full-duplex Applications
Choose an asynchronous, full-duplex 2-wire or 4-wire leased-line modem pair.
For Point-to-multipoint, Half-duplex Applications
Choose a modem which supports asynchronous, point-to-multipoint operation
over a 4-wire or 2-wire leased line. Typically these modems have a ‘master’ setting
for the modem connected to the master station and a ‘slave’ setting for the
modems that connect to remote stations.
For the master station, choose a modem that has the capability of holding the
modem carrier high so that no time is lost waiting for the modem carrier to turn
on and stabilize whenever the ‘master’ modem has data to transmit.
For the remote stations, choose a modem that can switch the carrier on and off,
whether transmitting or receiving, based on RTS/CTS signal handshaking with
the other remote stations. You need to use a switched modem carrier since the
stations share the same leased-line channel and would jam each other's data
transmission attempts if two or more remote station modems set their carriers
high at the same time. Using a half-duplex mode virtually guarantees that no two
remote stations will attempt to transmit data at the same time.
Supplier Maximum
Transmission Rate
Modem Model
DATA-LINC Group 33600/28800 DLM4000/DLM4500
Miille Applied Research
Co. Inc.
2400 166-100 (1746 chassis
mount)
2400, 14400, 28800,
and 33600
366-100 (DIN rain mount)
Rockwell Automation 28800 9300-RADKIT
28800 9300-RADES
(1)
(1) Ethernet dial-up modem
Phone Company
PLL PLL