Momentum Sales & Marketing Modbus Plus 170 PNT Series - Manual (Page 39)

Communication Access Registers
870 USE 103 00 May 2001 39
Configuration Registers
Overview This section describes the function and parameters for module timeout and module
ownership registers.
Module Timeout
Register
Function The module timeout register specifies the amount of time that outputs will be held in
their current state, if they are not updated by a new Modbus Plus Write command.
If the module’s holdup time expires before a new write command is received, all
outputs are set to logical 0 (zero).
Module Timeout
Register
Parameters The table below gives the parameters for module timeout registers:
Module
Ownership
Registers
Function Module ownership registers specify the addresses of up to three nodes which may
concurrently own write privilege to the adapter.
When the adapter first receives power, it will give sole write privilege to the first node
that writes to it. The adapter maintains an internal 60-second timer for handling the
write privilege, and will reserve sole privilege to that node as long at the node
continues to write within 60-second intervals to the adapter.
A node which currently owns the write privilege may write up to three words to the
adapter starting at reference 4F401. Each of the three words must correspond to a
valid node address in the range 1...64 decimal. With those addresses stored in the
adapter, any of those three nodes may then write to the adapter. This allows up to
three nodes to concurrently own write privilege to the adapter.
If writes continue to occur within the 60-second interval from any of the three
privileged nodes, no other node may write to the adapter. If the timer is allowed to
expire, any node may write to the adapter.
Parameters
Sharing Reference 4F001 (hex)
Field Length 1 word
Access Modbus Plus Read command
Units 1 = 10 milliseconds
Minimum Value 30 (300 milliseconds)
Maximum Value 6000 (60 seconds)
Default Value 100 (1 second)