Rockwell Automation 1395 Multi-Comm Hardware/Software - Manual (Page 43)

Chapter 3
Configuration & Interfacing
3–32
Token Pass With Data
This is a special mechanism built into the MCA board that allows the Drive
to transfer data between stations on a DH+ link along with the link token.
Refer to Figure 3–20. The amount of information passed is limited as
follows:
S Each station (each channel of an MCA board) can add two parameters
values to the list of values transferred with the token.
S Each station (each channel of an MCA board) can read up to four
parameter values from the available stations on the DH+ link.
Because this data is transferred with the network token, it is available to the
connected stations with a minimum of delay.
IMPORTANT: Data Highway + (DH+) is not designed for real time
control of data. Searching, monitoring large programs, and on-line
programming can degrade message throughput on this link since it can
perform only one of these functions at a time. Refer to the appropriate
PLC manual for details on the DH+ characteristics.