In this case, the Hima system will ultimately take over the fire protection on a gas drilling platform.For all these poti chips, you need to have CS-signals, for the 288 poti chips these are 288 CS lines. With MCP20S17, you have 16 lines per chip. With this PCA9698DGG,512, you have some more lines available. For setting values on the poti chip, the procedure is first to select the proper CS line by addressing the port expander (does not matter whether this is done by SPI or I2C or other), then transmit data to the poti chip by SPI.ghp wrote: ↑
21 Feb 2024, 19:38
For the CS-signals, there are IO expander with more than 16 bit available. E.g. PCA9698DGG,512 or use some FPGA chip.
When I search for this chip, I only find one with an I2C interface
But before going into details the full picture is not yet clear: The system to be build is "a test center for a Hima HIMax safety controller.". These "Hima HIMax safety controller" are as far I understand basically PLC with input lines and output lines. Where do the software controllable potentiometer come into this scenario, should they produce signals connected to input connectors of the PLC (digital, analogue??)? Do you want also capture output signals from the PLC to validate the system is working correkt ?
Why not use IO boards of another PLC as a test harness, just using modbus signals from a RPi to drive outputs and read inputs ?
We have to test the Hima here by simulating the devices that will be connected later, for example:
Analog fire detectors (0-20mA signal)
Analog gas detectors (4-20mA signal)
Digital flame detectors (end of line resistance: 10kohm; alarm resistance: 1kohm)
Digital smoke detectors (end of line resistance: 10kohm; alarm resistance: 1kohm)
Various push-buttons (end of line resistance: 10kohm; alarm resistance: 1kohm)
Then some outputs have to be tested where horns, flashing lights and solenoid valves will be connected later (EOL resistance: 1kohm)
So I have to change the resistor very often, that's why I was thinking about potis
I would like to monitor the following cards (often more than one of one type):
X-AI 32 01
X-DI 32 02
X-DO 24 01
Statistics: Posted by Sph3x — Thu Feb 22, 2024 2:16 pm