Is it possible to have different sampling rates in multi-board configuration? I tried using the scope application but I am unable to change the sampling rate independently.
No, that's unfortunately not possible.
It seems that the DRS4 chip and the evaluation boards are out of stock on the Radec website.
Is DRS4 being retired or something else is happening?
It is not quite clear to me yet how the input range is only determined by the front end and not the DRS4 chip. According to the datasheet, the selection of ROFS determines whether the input differential range is -0.5V to 0.5V (ROFS=1.55V) or 0V to 1V (ROFS=1.05V) or -0.05V to 0.95V (ROFS=1.1V).
As far as I understand, the input differential voltage cannot go further below -0.55V since the maximum ROFS voltage is 1.6V according to the datasheet).
Also in the DRS4 evaluation board 5.1 design, the output of the differential amplifier is AC coupled to the DRS4 chip.
I'd appreciate a lot your help.
A new software verison for the DRS4 Evaluation Board has been has been released. Version 2.1.3 adds a switch for the input range of the DRS4 board. Once can choose between -0.5V...0.5V and 0V...1V:
A board firmware update is not necessary for this. It was originally planned to have even a negative range -1V...0V, but this is not possible with the current board design. People who want to record negative pulses have to use an inverter to produce positive pulses. In a future version of the board it might be possible to include this functionality since this is determined by the analog front-end and not the DRS4 chip.
To achieve an input range of -1V to 0V, you need an external buffer which can shift this range into the DRS4 range of -0.5V to +0.5V. This external buffer has then to operate with bipolar power supplies, like -2.5V to +2.5V, which are not present on the evaluation board.