Omron CJ Series User Manual

5-25
5 Operation
CJ-series PROFIBUS Master Unit Operation Manual for NJ-series CPU Unit (W509)
5-5 I/O Communication Characteristics
5
5-5-1 I/O Data Configuration
5-5 I/O Communication Characteristics
 I/O Data Configuration
Each slave device defines its I/O data size, sequence and format by means of I/O modules, each of
which consists of one or more bytes, containing a PROFIBUS defined coding scheme. The I/O mod-
ules can define input data, or output data or both input and output data. The I/O modules are used to
configure the I/O data exchange process in the Master Unit and also to verify the amount of I/O data
to be exchanged with the slave device.
For modular slave devices the I/O modules are selected by the user from a list of available modules.
The modules usually have to be consistent with the physical I/O of the slave device. For non-modu-
lar slave devices there is only one I/O module, and can therefore not be selected by a user.
The selected I/O module bytes are sent over the PROFIBUS network to the slave device at startup,
using a Chk_Cfg message. The slave device has to check and approve the I/O modules sent by the
Master Unit, before I/O data exchange can be established.
 I/O Data Range Supported
TheCJ1W-PRM21 PROFIBUS Master Unit supports up to 4000 I/O modules, which can define a
total of up to 7168 words of input data and/or output data. The I/O module selection made per slave
by the user is also used to setup the I/O mapping, i.e. the definition of which I/O modules are
mapped to which CPU memory location.
This section discusses the aspects of I/O data exchange between the CJ1W-PRM21 PROFIBUS
Master Unit and the CPU.
 I/O Mapping Concept
The CJ1W-PRM21 PROFIBUS Master Unit provides an I/O mapping concept, based on the I/O
module selection for each slave device. Each selected I/O module can - depending on whether it
defines input and/or output data - be mapped to one of two input and/or output areas. Each of the
two input and output areas can be mapped to any CPU memory area location, independent of each
other. The I/O mapping must be setup using the CJ1W-PRM21 Master DTM, as provided with CX-
ConfiguratorFDT.
Mapping the I/O modules involves three steps:
• Allocate each I/O module to one or more of the Input/Output areas.
• Allocate each Input/Output area to CPU memory.
• Assigning user-defined variables to allocated Input/Output areas as required for the user pro-
gram.
 Default I/O Mapping Algorithm
When setting up the network, i.e. selecting the slave devices and I/O modules per slave, all input
modules will - by default - be allocated to Input area 1, all output modules will be allocated to Output
area 1. The following rules apply when allocating the I/O modules to the areas:
• I/O modules are mapped starting at the lowest address of an Input/Output area.
• I/O modules are mapped in ascending order according to slave device address.
5-5-1 I/O Data Configuration
5-5-2 Mapping I/O Data

Omron CJ Series Specifications

General

Brand	Omron
Model	CJ Series
Category	Controller
Language	English