Parker H Series - Image Table Mapping

Publication PSS-UM001A-EN-P – December 2016
DeviceNet
Scanner
DeviceNet
Subnet
DeviceNet
DeviceNet Poll Buffer
DeviceNet Strobe Buffer
DeviceNet COS/CYC Buffer
248 bytes
+ 2 bytes status
248 bytes
+ 2 bytes status
H Series Fieldbus DeviceNet Adapter
OUTPUT DATAINPUT DATA
Poll OR COS (inst 2)
248 + 2 bytes
6 + 2 bytes
I/O MAPPING
Subnet Modules
What is the H Series Fieldbus DeviceNet Adapter? 2-9
Image Table Mapping
Your adapter receives data from:
•master devices (e.g., scanners) - output data is then passed to
H Series Fieldbus I/O modules
•input modules - input data is passed to the scanner
The adapter must map the data it receives to its internal memory
before passing it to the appropriate device. The I/O map for a module
is divided into:
•read bytes - input and status bytes
•write bytes - output and confi guration bytes
The data is mapped by 3 buffers for input data (each representing
an I/O connection on the primary DeviceNet) and 1 buffer for output
data (representing data sent for Poll or COS connections on the
primary DeviceNet).
The number of read bytes or write bytes can be 2 or more. The
length of each I/O module’s read bytes and write bytes vary in size
depending on module complexity. Each I/O module supports at least
1 input byte or 1 output byte. Status and confi guration are optional,
depending on the module.
The following graphic shows how the adapter maps information.