Hi there, I am setting up a sigma delta modulator loop using a fixed step simulation and normal adders and delay elements. I get the weird Cannot solve algebraic loop involving 'sd_tb_fix/Product' because it consists of blocks that cannot be assigned algebraic variables, i.e., blocks with discrete-valued outputs, blocks with non-double or complex outputs, Stateflow blocks, or nonvirtual subsystems. --> Algebraic loop error with 'sd_tb_fix/Integer Delay1'. --> Algebraic loop error with 'sd_tb_fix/Sum2'. --> Algebraic loop error with 'sd_tb_fix/Sum3'. --> Algebraic loop error with 'sd_tb_fix/Sum1'. --> Algebraic loop error with 'sd_tb_fix/Integer Delay'. --> Algebraic loop error with 'sd_tb_fix/2 level quantizer'. --> Algebraic loop error with 'sd_tb_fix/Product'. I cannot believe simulink cannot get rid of a simple 2nd order intergrator in the discrte time domain: the integer delay blockshould account for the memory elements required to make simulink solve the differencies equations of the system ... or should I use anotherblock? I tried other (e.g. zero-order hold) w/o success any hints? thanks to whoever will help