Publication 1756-UM514B-EN-P - February 2003
8-6 Using the 1756-DHRIO Module in Remote I/O Applications
For daisy chain configurations, use Table 8.2 to determine the total
cable length you can use.
For proper operation, terminate both ends of a remote I/O network
by using the external resistors shipped with the 1756-DHRIO module.
Selecting either a 150W or a 82W terminator determines how many
devices you can connect on a single remote I/O network.
Table 8.2
Determining Cable Length
A remote I/O network using this
communication rate:
Cannot exceed this cable length:
57.6 kbps 3,048m (10,000 ft)
115.2 kbps 1,524m (5,000 ft)
230.4 kbps 762m (2,500 ft)
Table 8.3
Determining Resistor Rating and the Number of Devices Connected on Your
Network
If your remote I/O network: Use this
resistor rating:
The maximum
number of
physical
devices you
can connect on
the network:
The maximum
number of
racks you can
scan on the
network:
does not contain any of the
devices listed in Footnote 1,
regardless of communication
rate
82W 32 32
contains any of the following:
· 1771-AS
· 1771-ASB/A
· 1771-ASB/B
· 1771-DCM
· 1771-AF
150W 16 16
operates at 57.6kbps or
115.2kbps, and the network
does not support more than 16
physical devices
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