High-Frequency Relative Strength Index (RSI)

Query intraday minute-bar RSI (Relative Strength Index) for A-share securities via the market data service.RSI = 100 - 100 / (1 + RS), RS = average gain / average loss over N bars. Default period N=6. Values range 0-100; >70 overbought, <30 oversold.codes: comma-separated security codes (e.g. '600000.SH,000001.SZ').interval: minute bar width — 1/3/5/10/15/30/60.starttime/endtime: 'YYYY-MM-DD HH: MM: SS' intraday range.