Why does the online mode not work with the S5-PC converter TTY - RS 232?
The converter requires a power supply of +5 V on PIN 14, which is supplied by the controller interface.
This power supply is ensured with the following devices:
- AG135U/155U (CPU921, 920, 922, 928A, 928B, 923, 947, 947R, 948)
- IP252 (only AG115)
The pin assignment for the PC converter (MLFB 6ES5 734-1BD20) is displayed in the following figure:
Another cause might be that the device is equipped with a low-power interface. These interfaces provide much smaller voltages and currents on the send lines than normal RS232 interfaces. These interfaces are used on the RS232 side in many laptops/desktops and also in some USB adapters. For more information please refer to the manufacturer concerned.