Non-Cyclic Data Access - Emerson Unidrive M700 User Manual

7.4

Non-cyclic data access

Unidrive M supports the use of non-cyclic data access by user programs.
By simply enabling non-cyclic data (Non-cyclic mode enabled (S.02.035)) and
specifying a base parameter (Non-cyclic base parameter (S.02.036)), a user program
can be used to read or write a parameter either locally in the host drive or option
module, or in another drive or option module on the network.
Table 7.7 Non-cyclic data parameter functions
Parameter
Base address
(S.02.036)
Base address + 1
Base address + 2
Base address + 3
Base address + 4
Base address + 5
Base address + 6
The base address specifies the first parameter in a group of seven consecutive
parameters that will be used to read from or write to a parameter in the drive or option
module at the specified IP address by a user program.
The non-cyclic data access feature operates on a "state machine" principle, this means
that the commands must be sent in the correct sequence otherwise the parameter
access will fail.
The following diagram illustrates the operation of the non-cyclic parameter access state
machine.
138
Command
Status
Destination IP address wwwxxx
Destination IP address yyyzzz
Parameter address SMM
Parameter address PPP
Parameter value LSW or error code
Parameter value MSW
Function
0 = No command
1 = Check / Abort
2 = Read one parameter
3 = Write one parameter
0 = Idle
1 = Ready
2 = Processing
3 = OK
4 = Error
Bits
0 to 7 (LSB)
8 to 15 (MSB)
0 to 15
0 to 15
0 to 15
0 to 15
0 to 15
0 to 15
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