This demo, via BigCityMusic, shows the Analogue Systems rs390 Echo Module and rs200 in action:

The Analogue System rs390 is a very clean (24-bit converters) digital delay in Eurorack format with up to three seconds of delay time. There is a fun little range switch which allows you to cut your delay times on the fly You have CV control over the the delay time and the wet/dry mix. It is a stereo delay, capable of great sounding ping-pong delays but this is a mono video. 

We’re also using two rs200 Sequential Controllers to great effect as well as two rs150 Sequential Switches, the rs280 Signal Trigger/Clock Divider and a bit of the rs260 Voltage Quantizer (Quantiser!) for the chord modulation. The rs200 can send end pulse outs to trigger the next row and there are a centerline of switches to turn on or off trigger pulses for each row. Trigger 3 is on all the time.