hi everyone! i'm stuck problem, , can't figure out how solve it... i'm trying connect flow meter ( tsi 4000 series flowmeter ) arduino in order send specific commands set flow limits, type of sample (water, air, n2, etc) , on. i've bought rs232 shield arduino ( sparkfun rs232 ) , i'm using arduino mega. i'm trying send simple command, "?", , should receive "ok" message flow meter. problem i'm receiving bunch of squares, , don't know if it's coding problem or connection problem. i've attached black , green wire flowmeter (+5v , grownd) corresponding pins of shield, yellow , white wires of flowmeter (rs-232 out , rs-232 in) tx , rx pins on shield, , i've connected tx1 , rx1 on mega mtx , mrx pins on shield (photo attached). 2 jumpers connect mrx tx , mtx rx on shield. here code i'm using: code: [select] //serial i/o const int numreadings = 50; unsigned int flowread[numreadings]; // string read byte inread; // d...