MiCOM P921/P922/P923 - Schneider - error

P92x/EN CO/F22Page 8/10Connection DiagramsMiCOM P921/P922/P9232. PORTS CONNECTION2.1 Front port connection (RS232)The front communication port is provided by a 9-pin female D-type connectorlocated under the bottom hinged cover. It provides RS232 serial datacommunication (asynchronous RS232 connection according the IEC870requirements) and is intended for use with a PC locally to the relay (up to 15mdistance).The relay is a Data Communication Equipment (DCE) device. Thus the pinconnections of the relay’s 9-pin front port are as follows:Pin no. 2 Tx Transmit dataPin no. 3 Rx Receive dataPin no. 5 0V Zero volts commonNone of the other pins are connected in the relay. The relay should be connected tothe serial port of a PC, usually called COM1 or COM2. PCs are normally DataTerminal Equipment (DTE) devices which have a serial port pin connection as below(if in doubt check your PC manual):Pin no. 2 Rx Receive dataPin no. 3 Tx Transmit dataPin no. 5 0V Zero volts commonFor successful data communication, the Tx pin on the relay must be connected tothe Rx pin on the PC, and the Rx pin on the relay must be connected to the Tx pinon the PC, as shown in figure 5. Therefore, providing that the PC is a DTE with pinconnections as given above, a ‘straight through’ serial connector is required, i.e. onethat connects pin 2 to pin 2, pin 3 to pin 3, and pin 5 to pin 5. Note that a commoncause of difficulty with serial data communication is connecting Tx to Tx and Rx toRx. This could happen if a ‘cross-over’ serial connector is used, i.e. one thatconnects pin 2 to pin 3, and pin 3 to pin 2, or if the PC has the same pinconfiguration as the relay.MiCOM P921 relayLaptopBattery (phase 1)9 pin front portSerial data connector (up to 15 m)Serial communication port (COM1 or COM2)P0394ENcFIGURE 6: PCRELAY SIGNAL CONNECTION