Specifications

Rockwell Automation Publication AG-SG001G-EN-P - April 2015 45
Choosing Data Communication Equipment Chapter 3
Whether an application uses 2-wire or 4-wire leased lines, choose remote modems
that support switched modem carriers.
Modem Suppliers
See the following table for a listing of recommended analog leased-line modem
suppliers and respective modem models. Consult the vendor for information
about their product offerings.
Digital Leased-line ISUs
Integrated Service Units (ISUs) are the modem equivalents for the digital data
service lines. You can use the DDS network for point-to-point and point-to-
multipoint systems. Two components make up an ISU, as shown below:
• The data service unit (DSU) connects to the RS-232 link.
• The channel service unit (CSU) transmits the digital signal onto the
communication line.
Integrated service units are the DCEs for the digital data service lines.
The data rate for the ISU must match that of the DDS line. Some ISUs can
operate at multiple rates, but the rate of a DDS line is fixed.
Typical asynchronous DDS line speeds are 9600, 19.2 K, 38.4 K, and 57.6 K bits
per second.
Consult the vendor for information about their product offerings.
Supplier Transmission
Rate
Topology Modem Model
DATA-LINC
Group
1200 Point-to-point
(1)
(1) 2-wire maximum transmission rate is 300 baud.
LLM1100
(4)
(4) 1746 rack mount available.
Point-to-multipoint
(1)
33,600 Point-to-point
(2)
(2) 2-wire leased line only.
DLM4500
Miille
Applied
Research
1200 Point-to-multipoint
(3)
Point-to-point
(3)
(3) 2-wire or 4-wire leased line.
166-101 (1746 rack mount)
Point-to-multipoint
(3)
Point-to-point
(3)(1)
366-101 (DIN rail mount)
Phone Company
DDS DDS
DTE
DSU CSU
ISU
CSU DSU
ISU
DTE