NEC PX-61XM1A 61MP1 - Page 46

External Control Application These specifications cover the communications control of the plasma monitor by external equipment. Connections Connections are made as described below. plasma monitor External equipment e.g., Personal computer 1) Connector on the plasma monitor side: EXTERNAL CONTROL connector. Type of connector: D-Sub 9-pin male No. Pin Name 1 No Connection 2 RXD (Receive data) 3 TXD (Transmit data) 4 DTR (DTE side ready) 5 GND 6 DSR (DCE side ready) 7 RTS (Ready to send) 8 CTS (Clear to send) 9 No Connection 12345 678 9 2) Connector on the external equipment side: Serial port (RS-232C) connector. See the specifications of the equipment that is to be connected for the type of connector and the pin assignment. 3) Wiring Use a crossed (reverse) cable. Wire the cable so that each pair of data lines cross between the two devices. These data line pairs are RXD (Receive data) and TXD (Transmit data), DTR (DTE side ready) and DSR (DCE side ready), and RTS (Ready to send) and CTS (Clear to send). Communication Format 8 bit 8 bit 8 bit 8 bit 8 bit 8 bit 8 bit 8 bit Command 1 Unit ID 1 Unit ID 2 Command 2 Data length Data Check sum Command 1 Command 1, along with command 2, is a number used to distinguish each command. In the case of ACK, when the lower order 4 bits is FH (as in 3FH and 7FH), this indicates that the commands and data of the supported equipment have been received. When the lower order 4 bits is BH (as in 3BH and 7BH), this indicates that unsupported commands and data have been received. Unit ID 1 and Unit ID 2 Unit ID 1 and unit ID 2 are numbers used to identify the equipment that is to be connected. 60H is used for the plasma monitor and 80H is used for external control equipment such as a personal computer. 1) Unit ID 1: Indicates the equipment sending the signal 2) Unit ID 2: Indicates the equipment receiving the signal Command 2 Command 2, along with command 1, is a number used to distinguish each command. Check Sum (CKS), Error Processing, and ACK 1) The check sum described below and RS-232C odd parity are used together for a check of the received data. The check sum is the lower order 8 bits of one frame of sent or received data comprising the sum total of Command 1, Unit ID 1 and 2, Command 2, Data Length, and Data. Check Sum Example DFH 80H 60H 47H 01H 01H Command 1 Unit ID 1 Unit ID 2 Command 2 Data Length Data Total 208H 08H Check Sum L Communication Parameters (1) Communication system Asynchronous (2) Interface RS-232C (3) Baud rate 9600 bps (4) Data length 8 bits (5) Parity Odd (6) Stop bit 1 bit (7) Communication code Hex 2) Error Processing • When the communication interval is vacant for more than 4 ms, thereafter a received Command 1 will be recognized. If, at this time, meaningful data cannot be recognized, that data will not be recognized (as valid data). • An ACK will not be returned unless the receive data 39 error, the check sum error, and the receive data are all taken in.