The Industrial Raspberry Pi Forum

I have one question about AIO module. I want to use it for testing analog input of our embedded computer. Thus, I will be using OUT1 of the AIO module.
Input of our device supports 0-5V, 1-5V, 4-20mA, 0-20mA input on the same terminal. Our internal circuit is enabling 250Ω resistor when current input mode is selected.

Can I wire the I+ and V+ output with a shunt and connect it to our device? Then I would be using AIO in voltage output mode to test 1-5V and 0-5V range and in current mode to test 4-20mA and 0-20mA. Proper configuration of our device will be ensured before the output will be generated by AIO module.
Can you please confirm if such configuration is possible?

Hi AleksejsTarasovs,
if you operate the AIO module within the values specified in the AIO module data sheet, the circuit is irrelevant.

However, this type of alternating configuration during operation is not intended.
Specifically, the point is that you either output a voltage or a current at analog output 1.
As a result, you would have to create two PiCtory configurations and load them alternately during operation.
Of course, there are ways to implement this because the product makes it possible to do this by hand.

Is there a reason not to use the second analog output for this?

Hi Dirk,

I understand that we will have to re-load the configuration. The reason why we want to use the same output is because our DUT has both I and U inputs on the same terminal. Another reason is that we have 6 inputs we want to test simultaneously. If we will use OUT 1 for voltage and OUT 2 for current - we will need 6 AIO modules instead of 3.

In principle I want to understand following, lets assume operation in voltage output mode:

V+ will be connected to I+
V output mode will be selected and +5V will be generated by the AIO DAC
As V+ is connected to I+, +5V will be applied to the current output terminal

Can this cause damage to I+ output?
What is the impedance of the I+ output when it is disabled?

The same questions apply to current mode operation. Electrical values will be the same as our precision resistor is 250 ohms, thus at 20mA voltage will be +5V.

Thank you!