You can use the general equation for the triangle wave and implement it using simple simulink blocks
t = 0:0.01:10; % time
f = @(t,p) 2*abs(t/p-floor(t/p+1/2)); % t is time p is period, this create triangle wave in 0-1 range
plot(t,f(t,1))
plot(t,f(t,10))
