We noticed that when we power up RevPI [Compact], all 8 DIGITAL OUT pins switch to HI for a brief period, perhaps 5-10[ms]. This happens during every boot. What can I do?
yes, this is unfortunately a known issue.
We are currently working on this bug.
Unfortunately, we can't influence the behaviour.
The output pins on the Compact come directly from the compute module, and we have no influence on this behaviour at boot time.
Forum Entry: https://revolutionpi.de/forum/viewtopic.php?f=3&t=3329&p=12027#p12027
What is the XXX chip used to multiplex analogue to digital conversions (item 2)?
I have found the following from various specs, etc:
DAC is a Dual channel DAC082S085 chip connected to SPI0 of the Raspberry Pi
ADC is multiplexed from an XXX chip (I assume on SPI1)
Digital I/O is via the GPIO pins (GPIO00 - GPIO27).
Answer:
The multiplexer: DG408LE
the selection of the analog input is done via GPIO6, GPIO12 and GPIO13
GPIO | DG408LE |
|---|---|
GPIO6 | A0 |
GPIO12 | A1 |
GPIO13 | A2 |
How can I access these Digital Inputs /Outputs from Codesys?
There is a tutorial which describes the "blinking lights" using Codesys
https://revolutionpi.com/tutorials/beispiel-blinking-light-2/
I want to count rising edges with the RevPi Compact module, is that possible?
Yes, look here:
https://revolutionpi.de/forum/viewtopic.php?f=8&t=3062#p11153
What is the sampling rate or cycle time of the analogue inputs?
There is a discussion in the forum here, but it is in German
https://revolutionpi.de/forum/viewtopic.php?f=47&t=2945#p10564
Finally, the sampling rate is one second with piControl.
Higher sampling rates are possible without piControl
General information about the analogue inputs and outputs:
Tutorials on the topic with and without piControl
https://revolutionpi.com/tutorials/ein-ausgaenge-steuern-mit-picontrol-compact/
https://revolutionpi.com/tutorials/ein-ausgaenge-steuern-ohne-picontrol-compact/
I want to read out an analog PNP sensor with Python - how can I do that?
Have a look at this tutorial:
https://revolutionpi.com/tutorials/digitale-ein-und-ausgaenge-compact/?noredirect=en_US
Have a look at the BitMirror example:
https://revolutionpi.de/forum/viewtopic.php?f=6&t=2535&p=9196&hilit=bitmirror#p9196
The original discussion is here:
https://revolutionpi.de/forum/viewtopic.php?f=3&t=3020
Can the digital inputs work as counters?
No, this is not an integrated function of the RevPi Compact.
Can the digital outputs be used for PWM?
No, this is not an integrated function of the RevPi Compact.
When I look at the /var/log/kern.log, i am seeing a flood of messages "piControl i/o: missed xx cycles". Why is this error? How can we stop this error?
https://revolutionpi.de/forum/viewtopic.php?f=6&t=2998#p10787
I want to connect RS485 to PLC by I/O RS485 at Pin P and N (not USB) , What I have to do?
Have a look at our tutorial
https://revolution.kunbus.com/tutorials/serielle-geraete-anschliessen-compact/
There are two different supply voltages - device and IO channels. Is there a sequence to be observed?
No, the sequence does not matter. However, external devices should only be connected in a de-energized state and checked for correct wiring before commissioning to avoid destruction.
Digital Inputs and Outputs (Compact) - Industrial Raspberry Pi
I want to set a GPIO pin high and I don't use piControl. Why does the pin always go low?
The digital outputs are equipped with a watchdog. A watchdog is a component that monitors the functioning of other components in a system. In this case the digital outputs must be rewritten at least every 9 milliseconds. If this does not happen, the watchdog sets the digital outputs to “low” to establish a safe state! As the system might have crashed.
There is an undocumented interface on the RevPi Compact, can this be?
The HDMI interface is present but is not considered a warranted capability, therefore we do not warrant or support the HDMI interface.
Can the RevPi Compact be expanded, e.g. with I/O modules?
No, the RevPi Compact is not expandable.
Can the RevPi Compact handle measurements of negative Voltages?
No, the range is 0 - 10 V.
8 x analog Inputs |
2 x analog Outputs |
https://revolution.kunbus.com/revpi-compact/