rs232_20mA

Thursday, 2 October 2008

Posted by Joe

The Siemens SIMATIC S5 PLCs are programmed via a TTY serial interface (called also 20mA Current Loop). To connect a PC, which is normally equiped with RS232 ports, a converter is therefore required. In the AutoCAD R12 file there is a complete drawing of a RS232 to 20mA Current Loop converter, suitable for data access or programming functions. It works on all Simatic S5 CPUs (tested on 100U CPU 100/102/103, 115U CPU941/942/943/944, 135U CPU928, not tested on 150U and 155U) Since this is a PASSIVE converter (the current source is fetched from the PLC port), it is not possible to program other devices such as CP526/CP527 or OP393/OP396/OP5 etc., which require an ACTIVE (with separate power source) converter. Drawing 232_20mA

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Interfacing