Check your cable against the following diagrams. RS232 is limited to communicating at distances of < 50 Ft. For testing purposes connect a short cable directly from the computer to the machine.
The RS232 breakout box is connected inline with the cable to monitor the communications signals. It has about 10 tristate LED's which monitor the signal lines indicating one color for positive voltage, another for negative and off for 0V.
The following chart indicates the LED states for the listed conditions. The box is plugged is inserted on the control side of the cable.
S1 | S2 | S3 | |
SD | Toggling | Neg | Neg |
RD | Neg | Toggling | Neg |
RS, CS | Pos | Pos | Neg |
DR, CD, ER | Pos | Pos | Neg |
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S1 | Control Downloading Properly |
S2 | Control Uploading Properly |
S3 | Power up state or after DR OFF alarm occurred |
If any of the signals are 0V or at the incorrect level this indicates a problem with the device controlling that signal. When the breakout box is inserted between the cable and the CNC then SD, RS, CS, DR, CD, ER are controlled by the CNC and RD is controlled by the computer. If it was inserted between the computer and the cable then the exact opposite is true.