This section describes the driver routines that control the RS485 transceiver, and presents some ideas that may prove useful in designing a multi-drop data exchange protocol. Function prototypes for this function and other versatile serial I/O routines are defined in the COMM.H header file, and are described in detail in the Control-C Glossary. The QScreen Controller has two serial communications ports: a primary serial port called Serial 1 that supports both RS232 and RS485 protocols, and a secondary serial port called Serial 2 that supports RS232. The Jazz PLC series from Unitronics are not standard equipped with a RJ11 connector for serial communications. Page 61 ■ ASCII LED display data code (00H-1FH are blank.) Hex Code Display Char. 5.1. MODBUS-RTU transmission format MODBUS-RTU sends and receives binary data without a frame-synchronizing start code and de- fines the blank time to recognize the start of a frame. 6.2. Transmission format for inter-drive communication Data type is handled in hexadecimal notation and the transmission characters are treated with the binary (HEX) code.

The transmission format is basically the same to the case of binary mode. CRC values are generated by the transmission side that adds CRC to messages. The receiving side regenerates CRC of received messages and compares generation results of CRC regeneration with CRC values actually received. Use this function for the following case: When the data response from the inverter is too quick after the PC had sent the data to the inverter, PC process cannot get ready to receive the data, or when the USB/RS485, RS485/RS232C con- verter is used, changeover of sending and receiving data takes much time in the converter process. Synchronization can also be achieved by batch writing LED data parameters after changing the fol- lowing block communication mode parameters and by sending data by block communication. In this situation, bandwidth can be used for almost 100%. There are other implementations of RS485 networks where every node can start a data session on its own.

The flexible RS485 Cable is ideally suited for any industrial application. The other end of this cable connects to the M12 round connector on an OmniControl or a DCU controller. CBL01 RJ11-to-DB9 cable. Connects meter RS232 port to PC com port. One uses the data lines for 10/100 Ethernet, so that there are still 2 unused pairs in that cable. More and more people who work in plants need to understand how data from the field is transmitted to the control room and even to Manufacturing Execution Systems located in head offices situated considerable distances from the plant. 9600 baud, even parity, 8-bit length, 1 stop bit --- Reads in data to be sent to the inverter. If your application requires communicating with a device that expects to receive a parity bit, the generation of a parity bit and selection of even or odd parity, and whether there are seven or eight data bits in each byte, is performed by setting or clearing bits in the configuration registers SCI0CR1 for Serial1 and SCI1CR1 for Serial2.

The PT bit, with mask 0x01, determines whether even parity or odd parity is used if parity bit generation is enabled. Page 47 Communication command2 This command is enabled only when the communication command is enabled. Command processing will be executed only broadcast communication "0" and with those inverters that match set inverter numbers. 8.1. Communication commands (commands from the computer) Communication command (Communication number: FA00, FA04) Commands can be executed on inverter frequencies and operation stop through communication. Selects parity. ---- Enters a command. Selects a baud rate. Page 37 Setting example of parameters (2-wire RS485 communication) Parameters relating to the master side (example)  Master (transmission of output frequency (%) (100% at FH))  Selection of communication protocol (Toshiba inverter protocol) Communication baud rate  (ex. ) in the communication protocol selection parameters. 5.2. CRC Generation "CRC" is a system to check errors in communication frames during data transmission. Page 60 Block Communication Function for LED Display To display LED data for ASCII display that is synchronized to each digit, set data for each digit and validate this set data by display selection by communication (Communication Number FA65). Key Monitoring Procedure Set panel key selection (Communication Number: FA10) to "1" to set the external key mode.