Say there are Simulink buses in a model, Bus1 and Bus. How can we access the Bus1 info like which elements it has, their dimensions etc.
You can query data about buses by looking at the Signal Hierarchy or Compiled Bus Type of a signal.
However it appears that if you only have a virtual bus, you can only get the signal names and not the types/dimensions etc. The compiled bus type for a virtual bus is "VIRTUAL_BUS" so no information is provided.
This page discussed how to programmatically query a signal on a bus but as stated above, you will only find information, if you have a non-virtual bus.
Related
I'm relatively new to the I2C protocol and I have to write a c++ library for a particular sensor I have. I'm using a raspberry pi to interface and wiringpi (the i2c component) to handle the low level communications. This is a pretty standard library (read8bits, read16bits, readbuffer, same for write, that support register operations) so all I need to do is the specific, more higher level, sensor operations and export the sensor data to the main project.
But I have a problem, this particular sensor is a 10DOF IMU sensor
(https://www.waveshare.com/product/10-DOF-IMU-Sensor-C.htm) - which provides temperature pressure accelerometer magnetormeter and gyroscope information - and I've managed to get the pressure and temperature sensor reporting just fine but the MPU component is just odd...
So the sensor registers two I2C addresses, one for the pressure/temperature and one for the accelerometer/magnetometer/gyroscope.
Waveshare has a C library which I am using to understand how the sensor works and, for some reason the library is writing to different addresses (different from the registered ones). This particular sensor registers two addresses, 0x77 and 0x68, which I check with i2cdetect but consulting the code it has a particular address for the gyroscope and accelerometer and a separate one for the magnetometer (0xD0, 0x18 again) which should be the same.
So is it normal to do read/writes on addresses other than the registered ones? Would that even work? What am I missing?
The MPU-9255 is actually 2 separate I2C devices, the accelerometer and gyro are accessed on I2C address 0x68 (or 0x69 depending on the logic level of the AD0 pin), the the magnetometer is accessed on I2C address 0x0C.
The accelerometer and gyro I2C address are covered in section 7.2 of the MPU-9255 product specification. The magnetometer I2C address is in section 4.11.
The values that you are seeing in the code (0xD0 and 0x18) are shifted by 1, which leaves room for the I2C read/write bit.
0x68 << 1 = 0xD0
0x0C << 1 = 0x18
i need some help understanding a specific serial port connection from a sensor. I need to read data from the sensor and make some calculations in matlab or c++ (i will decide later)
The manufacturer only gives a chart with the following details:
Sensor Serial Port
Pin Number Mode Pin Description
I Trigger Input
I RS-232 Receive
O RS-232 Transmit
PWR Sensor Power (DTR)
PWR/GND Signal Ground
Not Used (Reserved)
Not Used (Reserved)
I/O RS-485 B Signal Pin
I/O RS-485 A Signal Pin**
So my question is: OK i know that pin 2 is used to receive data but how am i going to decode the volts stream into integers for example for my program? Also, i know that pin 4 gives power to the sensor. How do i know how many volts it has to give? Generally how am i going to learn all these details since the manufacturer does not give it?
Do you think Serial Port Analyzer Software will help?
Thanks very much in advance.
You might want to search for "DE-9 pinout YourSensorNameHere" in google or This page might be of some use to you. With most RS-232 you only need pins 2,3 and 5. With out more specifics about your sensor there isn't much SO can do for you.
I wrote a C S function which has a variable number of states depending on one parameter, which is passed to it (I'm using computational fluid dynamics and the parameter is the number of cells). I want to output a bus object from my S function that contains a temperature profile. Problem is I don't know the length of the output when I create the bus object in Simulink (in Bus Editor). Is there a way to dynamically set the size of the bus object from the C S function?
I think you can set the DimensionsMode property to "variable" instead of "fixed" (the default). See Simulink.BusElement and Variable-Size Signal Basics in the documentation for more details. Not sure how to code this in the S-function though.
What are the best practices for large scale modeling in Simulink when it comes to connecting blocks? Would you use the same structure for all I/O ports of your blocks to facilitate their interconnection (but obviously there will be a lot of redundant signals) or would you define custom structures for each I/O port type with only the necessary information?
For example:
A reactor is modeled as a single block with 4 inputs and 1 output:
I1. Feed which is a structure containing: Flow and Concentrations (7 species);
I2. Mass flow of enzymes - scalar;
I3. Mass flow of water - scalar;
I4. Outflow - which is adjusted by a controller to keep a constant mass in the tank - scalar;
O1. The outstream, which is a struct: Flow and Concentrations
(let's say 10 species).
Now imagine this reactor block is only a tiny piece of an entire process. There are enzymes and water tanks connected to it and some other downstream processes etc.
Would you use a unique structure for all IO ports (even if it scales up to 50-100 components but you would need less per block or 1 component like I2, I3 and I4 above which are scalars)? Is this regarded as bad programming practice?
Or would you customize the IO port structure for each block? Of course you would group them somehow and make reuse of them but with no redundant information.
Thanks!
You might find the following useful: http://www.mathworks.co.uk/videos/tips-and-tricks-for-large-scale-model-based-design-part-2-81873.html.
I would personally use a single bus input and a single bus output for your reactor block. You can then group buses together to form larger bus signals as you move up the hierarchy of your model. Look at the Bus Creator and Bus Selector blocks.
Is there anyway to simply append a signal to a bus in Simulink? This doesn't seem to be that difficult, but I haven't found a nice way to do it. I can only think of two ways to currently accomplish this:
Select all signals in the bus with a bus selector, then create a bus with all those signals plus the signal to be append using a bus creator. (this is what I am currently doing)
"Pre-allocate" a space in the bus for the signal to be append beforehand then simply replace its value with the value of the actual signal using a bus assignment block.
Is there a reason as to why Simulink cannot append a signal to a bus? Is it because on the backend they are represents as structures (or MATLAB's equivalent) and a property cannot be added to a structure at runtime?
If you are using a bus object, you can use the Bus Editor to add a bus element to an existing bus.