16-Port EIA 232 signal voltage levels
The signal is in the mark state when the voltage on the interchange circuit, measured at the interface point, is less than -3 V dc with respect to the signal ground. The signal is in the space state when the voltage is greater than +3 V dc with respect to the signal ground. The region between +3 V dc and -3 V dc is defined as the transition region and is not a valid level. Voltage less than -15 V dc or greater than +15 V dc is also not a valid level.
During the transmission of data, the mark state denotes binary state 1 and the space state denotes binary state 0.
For interface control circuits, the function is on when the voltage is greater than +3 V dc with respect to the signal ground and is off when the voltage is less than -3 V dc with respect to the signal ground. See the following table for EIA 232 signal levels.
| Interchange Voltage | Binary State | Signal Condition | Interface Control Function |
|---|---|---|---|
| + Voltage | 0 | Space | On |
| - Voltage | 1 | Mark | Off |
The electrical characteristics of the 16-Port asynchronous EIA 232 adapter ports conform to the EIA Standard 232C dated October 1969 and to the EIA Standard 232D dated January 1987.
The adapter ports meet the functional requirements for asynchronous operation (start-stop protocol) as described in the EIA Standard 232C dated October 1969 and in the EIA Standard 232D dated January 1987.