Rockwell Automation 2080-LC50 Micro800 Controllers: Getting Started with CIP Client Messaging - Manual (Page 57)

Rockwell Automation Publication 2080-QS002A-EN-E - April 2013 51
Programming Tips and Recommendations for Micro800 CIP Messaging Instructions (MSG) Appendix F
Supported Data Packet Size
for CIP Serial Function For Micro830 and Micro850 controllers, both embedded serial port and plug-in
serial ports can support CIP serial communication. CIP serial communication
data packet includes user data and CIP packet header.
When working as a CIP serial client, Micro830/Micro850 serial ports can
support a maximum of 490 bytes of read/write user data. This maximum
specification applies to CIP serial data packets with a minimum packet header
size. When the size of a packet header is bigger than the minimum packet header
size, the maximum size of user data that the CIP client can support is less than
490 bytes. If data packet size is greater than the maximum data size supported by
the CIP client, the function block reports an error (0x21) and a sub-error (0x33).
When working as a CIP serial server, Micro830/Micro850 serial ports can
support a minimum of 255 bytes of read/write user data. This minimum user
data size specification applies to CIP serial data packets with maximum packet
header size. When the size of CIP packet header is less than the maximum packet
header size, the CIP client can support data packet size that is greater than the
minimum specification (that is, greater than 255 bytes). However, if user data size
is greater than the maximum data size supported by the CIP server function, the
CIP data packet could be dropped, and the client will time out.
Programming Tips for COP
Instruction The following tips apply when programming with the COP instruction.
1. Both Source and Destination data has to be in the form of array. If only one
variable needs to be copied, define the variable as one element array.
IMPORTANT For CIP serial server function, it is recommended not to read/write more
than 255 bytes of user data in a single CIP message.