Hi,
Your colleagues in the UK are currently dealing with my query and are being very helpful, thanks. I've inserted 'dummy' channels between 'real input' channels, grounded all unused channels, grounded one end of the thermocuple through a resistor, and have deliberately kept all other channels at 0V, but the problem still remains for both fast and slow sampling rates. I will post another reply to this thread when the issue is resolved.
Regarding the range: I define my group of channels with the 'NI345X_Set_Scan_List' function. The 'NI345X_Set_Auto_Zero' function (as well as functions for powerline frequency, reading rate, etc.), doesn't take a channel list because as its on-line documentation indicates, it "sets auto zero for all channels". However, the 'NI435X_Set_Range' function *has* an argument for a channel list, which implies to me that ranges can be independently set for each channel in the list. If not, then there's no point in having this argument, as the channel string is already defined by 'NI345X_Set_Scan_List'. If my understanding of your message is correct however, the DAQ will only read at a setting appropriate to the highest range specified using 'NI435X_Set_Range', which would indeed appear to make its argument for a channel string both redundant and a little misleading vis a vis capability. If this is the case though, 'NI435X_Set_Range' need only be called once for each scan list configuration and I have overestimated the capabilities of the NI4351. I cannot afford the overhead of continously reconfiguring the hardware as you suggest, because I need to feed an averaged temperature reading to a PID algorithm once every second.
Thank you for your feedback though, and I would be grateful for clarification on the above please.
Regards,
John.
