1 the leader in industrial data communication solutions troubleshooting tips
DESCRIPTION
3 Larry’s Rockwell Tips General Comments Rockwell’s example PLC programs work very well Noisy phone lines or less than ideal wireless links: Greater retries (latency) Do not exceed throughput capacity Consolidate data to minimize number of MSGs A few MSGs with larger amounts of data is fasterTRANSCRIPT
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The Leader in Industrial Data Communication Solutions
Troubleshooting Tips
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Troubleshooting Tips General
Clarify symptoms Isolate comms from PLC network Perform loopback or PING tests Check diagnostic information If communications are verified, consider PLC system:
Improper RSLinx configuration? Latency causing timeouts? Program problems?
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Larry’s Rockwell Tips General Comments
Rockwell’s example PLC programs work very well Noisy phone lines or less than ideal wireless links:
Greater retries (latency) Do not exceed throughput capacity Consolidate data to minimize number of MSGs
A few MSGs with larger amounts of data is faster
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Larry’s Rockwell Tips SRM Wireless Ethernet Modem
Equipment attached to remote modems do not directly communicate
Use Ethernet switches, not hubs IGMP snooping preferred
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Larry’s Rockwell Tips DF1 Protocol
No limitations with Data-Linc modems Prefer STD Polling Mode (multiple MSGs per scan) DF1 master PLC will relay MSGs “Missing Remote” Failure (not with Logix platforms)
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Larry’s Rockwell Tips DF1 Protocol
“Missing Remote” Failure (not with Logix platforms)
On SLCs do this:
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Larry’s Rockwell Tips NOT this:Reason: With SLC or MicroLogix
multiple enabled MSGs are queued in the transmit buffer. While queued their Timeout interval is timing. If a current MSG times out all others queued will timeout giving the appearance that multiple slaves have failed.
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Larry’s Rockwell Tips Multi-drop Channel Pass-Through is a wonderful
thing!
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Larry’s Rockwell Tips Logix Platforms
These machines can REALLY move data and quickly overwhelm a radio network. As always, do not exceed the network’s throughput capability.
Be mindful of RPI. Ten 32 bit words with an RPI of 10 milliseconds is 32kbps without even considering protocol overhead!
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Larry’s Rockwell Tips RSLinx
Red Xs can appear intermittently when using low baud rates (1200 baud) depending on communication quality and other communication traffic. This is normal.
DF1 Polling Master Driver. The parameters Max Pkt Wait Time (Sec) and Max
Retransmission Wait Time (Sec) and not well documented. Values that have worked well:
Max Pkt Wait Time: 8 (default 150) Max Retransmission Wait Time: 15 (default 600)
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Larry’s Rockwell Tips
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The Leader in Industrial Data Communication Solutions
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