SCADA Polling Collision Predictor
Calculate physical transmission time to prevent Modbus RTU timeout errors and buffer overflows.
Absolute Minimum Physical Time Required
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ms
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Enter your parameters above to see the analysis.
View Modbus RTU Timing Math
1. Character Time: Standard Modbus RTU uses 11 bits per character (1 start, 8 data, 1 parity/none+stop, 1 stop).
2. Request Frame: Master query is fixed at 8 bytes.
3. Response Frame: Slave response is 5 bytes + (Registers × 2 bytes).
4. Silent Intervals: Modbus standard requires a 3.5 character silence between frames (7 characters total per round trip).
Formula:
2. Request Frame: Master query is fixed at 8 bytes.
3. Response Frame: Slave response is 5 bytes + (Registers × 2 bytes).
4. Silent Intervals: Modbus standard requires a 3.5 character silence between frames (7 characters total per round trip).
Formula:
Total Time = [(8 + Response Bytes + 7) × 11 bits / Baud Rate] × 1000 + Slave Processing Delay.Is your SCADA too fast for your serial bus?
Increasing the SCADA timeout setting is only a band-aid that freezes your software. The architectural solution is to decouple the networks using Edge Caching.
The Hardware Fix
Protocol Gateways with “Storage Modbus”
Our gateways autonomously poll the RS485 bus at safe 9600 speeds, caching data in local RAM. When your Gigabit SCADA polls at 100ms, the gateway responds instantly from memory—eliminating timeouts.
View Smart Gateways →
Engineering tools designed for OT professionals by Valtoris.
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