Bradley Smoker PLC-5 Polling Inactive Priority Stations, Changing Modes, Follow these guidelines

Communicating with Devices on a Serial Link 10-5

Polling Inactive Priority Stations

Through the channel configuration feature of your programming software, you can choose to poll one or all of the inactive priority stations when the PLC-5 controller is in master mode on channel 0. The default selection is to poll one inactive priority station during each polling sequence.

If you choose to poll all inactive stations, you are alerted immediately when an inactive station becomes active; you do not have to wait for all of the other polling sequences to complete. Polling all inactive stations might slow down channel performance.

Changing Modes

Cabling

Configure channel 0 of the controller to change communication modes via:

•the channel configuration screen in your programming software (in program mode only) ; or

•communication mode change characters (ASCII control characters) sent remotely to the controller, which switches modes

The following table lists the maximum cable lengths you can use with channel 0.

Port	Transmission	Maximum Cable
	Rate(s)	Length

RS-232C	All	15 m (50 ft)
RS-422A	All	61 m (200 ft)
(compatible)
RS-423	All	61 m (200 ft)

IMPORTANT

Follow these guidelines:

•When channel 0 is configured for RS-422A compatibility, do not use terminating resistors anywhere on the link.

•When channel 0 is configured for RS-422A (compatible) and RS-423, do not go beyond 61 m (200 ft). This distance restriction is independent from the transmission rate.

Publication 1785-UM012D-EN-P - July 2005