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Do-more CPUs and Do-more Designer Software / Ring buffer for fault logging
« Last post by Bobby Tables on March 26, 2026, 01:05:52 PM »I've been lurking for a while but this is my first post.
Background for the issue:
I want to record the machine state as a file that is able to be loaded into DmDesigner on the simulator so I can troubleshoot the machine state remotely. The BACKUP instruction takes multiple scans to complete so machine states may change before it is done.
I would also like to log important state history leading up to the fault in a ring buffer to be logged in the event of a fault. So as to not bog down the system and the log with writing non important events.
I want to log fault bits being turned on at rungs that trigger them 0->1. The machine itself has a fault reset switch that will turn off the faults when the cause has been resolved. But I want to use FILELOG or DMLOGGER as an event log so I know what rung caused the fault, important machine state bits, etc. so errors can be reproduced.
To solve the multi scan BACKUP issue I would like to similarly buffer the machine state of the last few scans before the fault occurred.
The issue is FILELOG and DMLOGGER do not have a ring buffer to allow the order and time to be preserved. And I have had trouble finding example of implementing a ring buffer for an event log on here.
Question for the forum:
The implementation I want is
---|state_variable1 rising contact|---(write to buffer)
---|write_complete_bit|----(MATH: buffer_length=buffer_length+1)
---|state_variable1 falling contact|---(write to buffer)
---|write_complete_bit|----(MATH: buffer_length(V###)=buffer_length+1)
---|fault_on_bit|----(read_from_buffer_trigger_bit)
[fault handling logic follows and the machine enters a stopped state]
----|machine_is_stopped_state_bit|------[logic to read from buffer in order using for loop and/or buffer read instruction for FIFO into FILELOG or DMLOGGER]
Or creating an image reading from a different larger buffer with the whole machine state in the last few scans
---|read_1_buffer_entry_complete_bit|----(MATH: buffer_length=buffer_length-1)
---|EQU buffer_length=0|-----(buffer_length_is_full_bit)
The FIFO buffer by default doesn't seem to necessarily be a ring buffer implementation. Is there a way to modify it to work like one?
for reference
https://en.wikipedia.org/wiki/Circular_buffertcplclib_tc2_utilities/35413643.html&id=
Background for the issue:
I want to record the machine state as a file that is able to be loaded into DmDesigner on the simulator so I can troubleshoot the machine state remotely. The BACKUP instruction takes multiple scans to complete so machine states may change before it is done.
I would also like to log important state history leading up to the fault in a ring buffer to be logged in the event of a fault. So as to not bog down the system and the log with writing non important events.
I want to log fault bits being turned on at rungs that trigger them 0->1. The machine itself has a fault reset switch that will turn off the faults when the cause has been resolved. But I want to use FILELOG or DMLOGGER as an event log so I know what rung caused the fault, important machine state bits, etc. so errors can be reproduced.
To solve the multi scan BACKUP issue I would like to similarly buffer the machine state of the last few scans before the fault occurred.
The issue is FILELOG and DMLOGGER do not have a ring buffer to allow the order and time to be preserved. And I have had trouble finding example of implementing a ring buffer for an event log on here.
Question for the forum:
- Does anyone have references on how to implement an event log ring buffer in DmDesigner?
- And has anyone been able to buffer the BACKUP instruction?
The implementation I want is
- A fault bit 0->1
- The event is logged in a ring buffer
- The log is only sent to FILELOG or DMLOGGER upon the machine stop occurring and it waits until the loging is complete before restarting
- The ring buffer is emptied
- The machine enters the restarting state
---|state_variable1 rising contact|---(write to buffer)
---|write_complete_bit|----(MATH: buffer_length=buffer_length+1)
---|state_variable1 falling contact|---(write to buffer)
---|write_complete_bit|----(MATH: buffer_length(V###)=buffer_length+1)
---|fault_on_bit|----(read_from_buffer_trigger_bit)
[fault handling logic follows and the machine enters a stopped state]
----|machine_is_stopped_state_bit|------[logic to read from buffer in order using for loop and/or buffer read instruction for FIFO into FILELOG or DMLOGGER]
Or creating an image reading from a different larger buffer with the whole machine state in the last few scans
---|read_1_buffer_entry_complete_bit|----(MATH: buffer_length=buffer_length-1)
---|EQU buffer_length=0|-----(buffer_length_is_full_bit)
The FIFO buffer by default doesn't seem to necessarily be a ring buffer implementation. Is there a way to modify it to work like one?
for reference
https://en.wikipedia.org/wiki/Circular_buffertcplclib_tc2_utilities/35413643.html&id=
