Daisy Chain Amplifier Bus Timing Synchronization via Echo Delay Compensation
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Solution Overview
Problem
Existing data transmission/reception systems via daisy chain type serial bus face issues with propagation delays due to long cable lengths, leading to delayed data reception and potential failure in transmitting data from downstream units to the numerical controller.
Innovation Solution
Incorporating a delimiting position change mechanism and bit position setting storage means to adjust the bit position of data delimiters, and using an echo back method to measure and compensate for propagation delays, allowing for the insertion of idle time data to ensure timely data transmission and reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If cable length between units is increased, then ease of installation and system flexibility are improved, but propagation delay increases causing data reception timing to shift and transmission failure
Solution Approach 1:
The system performs preliminary delay measurement using an echo back method before normal data transmission. The numerical controller sends a delay measurement command to each amplifier, which measures the round-trip time and calculates the one-way propagation delay. This preliminary action allows the system to know the exact delay characteristics before actual data transmission begins, enabling proper timing synchronization.
Solution Approach 2:
The system dynamically changes the transmission timing parameters based on the measured propagation delay. Each amplifier adjusts its data transmission start time by adding the calculated one-way delay to the base timing. This parameter adjustment ensures that despite varying cable lengths, all amplifiers transmit their data in the correct sequence (A1 first, then A2, then A3) without timing conflicts.
2Length of stationary object
If cable length is increased beyond a certain limit, then installation flexibility is improved, but data transmission reliability deteriorates due to delayed reception and transmission failure
Solution Approach 1:
The system uses feedback from the echo back measurement to adjust transmission timing. Each amplifier measures the actual signal propagation time through the cable and uses this feedback information to synchronize its data transmission with the numerical controller's reception window. This closed-loop timing synchronization maintains transmission reliability regardless of cable length.
Solution Approach 2:
The transmission timing is made dynamic rather than fixed. Each amplifier calculates its specific transmission start time based on the measured propagation delay, creating a dynamic timing scheme that adapts to the actual cable characteristics. This allows the system to accommodate varying cable lengths while maintaining reliable data transmission.
3Device complexity
If fixed delimiting position is used for data transmission, then device complexity is reduced, but adaptability to different cable lengths deteriorates
Solution Approach 1:
The system performs preliminary delay measurement and calculation before normal operation. By measuring the propagation delay once during system initialization or configuration, the system establishes the timing parameters needed for all subsequent data transmissions. This preliminary action eliminates the need for complex real-time adjustments during normal operation.
Solution Approach 2:
The system changes the transmission timing parameter (start time offset) based on the measured propagation delay. Instead of changing the data structure or delimiting positions, the system adjusts the temporal parameter of when each amplifier transmits its data. This simple parameter change provides adaptability to different cable lengths without increasing structural complexity.
Data Source
AI summary
An amplifier (unit) linked via a daisy type serial bus sends a transmission start signal SC and then sends the local data DATAn. If data from an amplifier at the downstream side is not received before transmission of the local data DATAn is completed, the delimit of the data from each amplifier is changed by adding an idle time data TIDD.