This is the solution I came up with, it's not elegant so I would like to know if someone came up with something better. I created a subsystem with the following blocks inside:
The Rate Limiter block runs in variable step solvers but doesn't have input ports for rate limits, these are set in the Parameters inside the block. It so happens that you can change these parameters while the simulation is running, either manually by double clicking the block or by using the set_param command. Here I am using an embedded MATLAB function (the block named "Set_param for RateLimit") to do this. The code inside this block is as follows:
function RtLim(up,dn)
eml.extrinsic('evalin');
eml.extrinsic('set_param');
eml.extrinsic('num2str');
persistent up_z;
persistent dn_z;
if (isempty(up_z))
up_z = 0.99*up;
dn_z = 0.99*dn;
end
if up_z ~= up || dn_z ~= dn
evalin('caller', 'blocknameWS = gcb;');
blockname = evalin('caller', 'blocknameWS(1:end-35);');
blockname = [blockname 'Rate Limiter'];
set_param(blockname, 'risingSlewLimit', num2str(up));
set_param(blockname, 'fallingSlewLimit', num2str(dn));
end
up_z = up;
dn_z = dn;
end
This code builds the full block name of the rate limiter block and stores the string in the variable "blockname". Then it uses that in the set_param command. That way the subsystem can be copied and pasted in other areas of the model and renamed and it will work without having to change anything inside (Note: careful if you rename the rate limiter block since the code depends on that name and also if you rename the Embedded MATLAB function since the code depends on that name being a certain length. Also note that here I am checking if the rate settings have changed before calling the evalin and set_param commands (in my case they only change occasionally so the model executes faster if I don't constantly execute the evalin and set_param commands for nothing).
