Omron CJ1W-DRM21 - Master Remote I;O Communications; Allocations

4 Remote I/O Master Communications
4-2
CJ-series DeviceNet Units Operation Manual for NJ-series CPU Unit(W497)
4-1 Master Remote I/O Communications
Remote I/O communications are used to automatically transfer data between slaves and the CPU Unit
without any special programming in the CPU Unit under which the Master Unit is mounted.
z Master Communications
Note A CJ-series DeviceNet Unit can function as either a master or slave in remote I/O communi-
cations and it can even function as both a master and a slave at the same time. Change
*_Sw1MstrEnblCmd (Master Enable Switch) to TRUE to set the CJ-series DeviceNet Unit to
function as a master. Once master communications are enabled, the Unit will continue to per-
form master communications regardless of whether the power is turned OFF and back ON
again.
Change *_Sw1MstrDsblCmd (Master Disable Switch) to TRUE to stop master communica-
tions. Master communications are the focus of this section.
In the following descriptions, a CJ-series DeviceNet Unit set to function as a master is
referred to as a "Master Unit" and a CJ-series DeviceNet Unit set to function as a slave is
referred to as a "Slave Unit".
All slaves are allocated in the I/O memory area in the NJ-series CPU Unit to which the Master Unit is
mounted. They are allocated using one of the following methods:
1) Fixed allocations
2) User-set allocations
Note With either fixed or user-set allocations, to access the area where each slave is allocated from
the user program, a user-defined variable that specifies the AT specification of that area needs
to be defined.
4-1-1 Allocations
DeviceNet
Remote I/O communications
Slaves
CJ-series DeviceNet Unit (master)
NJ-series CPU Unit