As we learned earlier in this chapter, channels represent the field signals that can be wired to, and processed by, the module. But how do we reference these channels in our programs and read their values or write new values to field devices? In this section, we will learn the standard syntax for addressing I/O channels. Individual channels on a module can be referenced in your Logix Designer/RSLogix 5000 programs using its address. An address gives the controller directions to where it can find a particular piece of information about a channel on a module. The following diagram breaks down the syntax of a module value reference:
The first field of an address specifies the location of the channel (and is followed by a colon). The location can either be local to the controller or on a remote rack, which connects through a network adapter or bridge module. So, this field can be one of the following bridges:
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