Bradley Smoker PLC-5 user manual Transferring Discrete Data to Controller-Resident I/O

Communicating with Controller-Resident I/O 5-3

Transferring Data to Controller-Resident I/O

APLC-5 controller transfers discrete and block-transfer data with controller-resident I/O.

Transferring Discrete Data to Controller-Resident I/O

a b

The controller scans controller-resident local I/O synchronously and sequentially to the program scan.

The controller-resident rack exchanges discrete I/O information with the I/O image table during housekeeping.

x y

			Housekeeping
I/O Image
Table		Update
		I/O image
	Data
	Exchange

Controller-

Resident

RackLogic Scan

a

write outputs

b	Program Scan
read inputs

Immediate I/O

IOT (x)

IIN (y)

See explanation below.

Transferring Immediate I/O Requests

The controller responds to immediate input (IIN) and immediate output (IOT) requests during the logic scan. The logic scan is suspended at the request for immediate input/output data. The logic scan resumes after obtaining the data and fulfilling the request.

IIN data transfers directly to and IOT data transfers directly from I/O modules in controller-resident I/O and extended-local I/O chassis. With remote I/O, only the remote I/O buffer is updated. For more information, see Appendix D.

TIP

When you place I/O modules, do not place a block-transfer module next to or in the same module group as an input module that you plan to use for immediate I/O. Place the modules in non-adjacent slots. Placing input modules for immediate I/O next to block-transfer modules can result in a -5 Block-Transfer Read error.

Publication 1785-UM012D-EN-P - July 2005