Bradley Smoker PLC-5 Network using a daisy chain or trunk line/drop line, Configuration

Communicating with Remote I/O 6-5

Cable Design Guidelines

Trunk line/drop line considerations:

When using a trunk line/drop line configuration, use 1770-SC station connectors and follow these cable-length guidelines:

trunk line-cable length*depends on the communication rate of the link

drop-cable length*30.4 m (100 cable-ft)

For more information about designing trunk line/drop line configurations, see the Data Highway/Data Highway Plus/Data Highway II/Data Highway-485 Cable Installation Manual, publication 1770-6.2.2.

	Specify 1770-CD (Belden 9463) cable. Connect a remote
TIP
	I/O network using a daisy chain or trunk line/drop line
	configuration.

Verify that your system’s design plans specify cable lengths within allowable measurements.

	The maximum cable length for remote I/O depends on the
IMPORTANT
	transmission rate. Configure all devices on a remote I/O
	link to communicate at the same transmission rate.

For daisy chain configurations, use this table to determine the total cable length you can use.

A Remote I/O Link Using	Cannot Exceed this
this Communication Rate	Cable Length
57.6 kbps	3,048 m (10,000 ft)
115.2 kbps	1,524 m (5,000 ft)
230.4 kbps	762 m (2,500 ft)

IMPORTANT

If you select the baud rate as 230.4 kbps, and you are using the serial port or a PLC-5 coprocessor, use channel 2 for better overall system performance.

For proper operation, terminate both ends of a remote I/O link by using the external resistors shipped with the programmable controller. Selecting either a 150Ω or 82Ω terminator determines how many devices you can connect on a single remote I/O link.

If Your Remote I/O Link	Use this Resistor	The Maximum number	The Maximum
	Rating	of Physical Devices You	Number of Racks You
		can Connect on the Link:	can Scan on the lLnk
operates at 230.4 kbps	82Ω	32	16
operates at 57.6 kbps or 115.2 kbps and no
devices listed in the following table are on
the link
contains any device listed in the following	150Ω	16	16
table
operates at 57.6 kbps or 115.2 kbps, and you
do not require the link to support more than
16 physical devices.

Publication 1785-UM012D-EN-P - July 2005