Check out PLC OPEN organization for vendors. While it is true that most PLC vendors who support IEC 61131 will support function block diagram programming - it is not necessary to say that all support it. Be careful in your selection process - make sure they are approved by PCL OPEN and then...
I noticed some people have responded to you with the IEC 61131-3 programming standard but have not given you the correct link for more information. The association responsible for this standard is PLC-OPEN and can be found at www.plcopen.org. The company I work for WAGO offers a fully...