By default, the 4B uses Gerber's proprietary language which SignGo does not support. However, many 4B's were fitted with either the "Thermazone" or "Omni" card that effectively converted them to accept the standard HPGL language. If your 4B happens to be fitted with either of these cards you can drive it from SignGo using the Thermazone driver. These cards end with a 9 pin serial connector.