在傳統(tǒng)的I/O系統(tǒng)中，控制器輪詢輸入模塊以獲得其
輸入狀態(tài)。ControlLogix系統(tǒng)中的數(shù)字輸入模塊不可用
由控制員調(diào)查。相反，模塊生成（“多播”）數(shù)據(jù)
要么是在狀態(tài)改變時，要么是周期性的。更新的頻率
取決于配置期間選擇的選項以及
輸入模塊所在的網(wǎng)絡(luò)。因此，輸入模塊是一個
輸入數(shù)據(jù)的生產(chǎn)者，而控制器是數(shù)據(jù)的消費者。
控制器還可以生成數(shù)據(jù)供其他控制器使用。這個
生產(chǎn)和消費的數(shù)據(jù)可由多個控制器通過網(wǎng)絡(luò)訪問
ControlBus背板和ControlNet網(wǎng)絡(luò)。這些數(shù)據(jù)
交換符合生產(chǎn)者/消費者模式。
本手冊提供了生產(chǎn)商/消費者模型的示例
適用于ControlLogix和PLC-5C控制器。
請注意，PLC-5術(shù)語與
ControlLogix。PLC-5C“發(fā)送預(yù)定消息”功能正常
相當(dāng)于ControlLogix的“生產(chǎn)標簽”PLC5“預(yù)定接收
message“在功能上等同于ControlLogix“consumed tag”In traditional I/O systems, controllers poll input modules to obtain their
input status. Digital input modules in the ControlLogix system are not
polled by a controller. Instead, the modules produce (“multicast”) their data
either upon a change of state or periodically. The frequency of update
depends upon the options chosen during configuration and where on the
network the input module resides. The input module, therefore, is a
producer of input data and the controller is a consumer of the data.
The controller can also produce data for other controllers to consume. The
produced and consumed data is accessible by multiple controllers over the
ControlBus backplane and over the ControlNet network. This data
exchange conforms to the producer/consumer model.
This manual provides examples of the producer/consumer model as it
applies to ControlLogix and PLC-5C controllers.
Note that PLC-5 terminology differs slightly from that used by
ControlLogix. A PLC-5C “send scheduled message” is functionally
equivalent to a ControlLogix “produced tag.” A PLC5 “receive scheduled
message” is functionally equivalent to a ControlLogix “consumed tag.”