User manual HANNA INSTRUMENTS HI 700710

[. . . ] HI 700 / HI 710 Series Process, Panel-mounted, Microprocessor-based, Conductivity and TDS Controllers Instruction Manual Dear Customer, Thank you for choosing a Hanna Product. This instruction manual has been written for the following products: HI 700221 EC controller with dual setpoint, ON/OFF and PID control, analog output. HI 700222 EC controller with dual setpoint, ON/OFF and PID control, RS485 port. HI 710221 HI 710222 EC and TDS controller with dual setpoint, ON/OFF and PID control, analog output. [. . . ] Internal termination: none Excel© Copyright of "Microsoft Co. " Lotus 1-2-3© Copyright of "Lotus Co. " Windows® registered Trademark of "Microsoft Co. " 29 CONNECTIONS The connections for the 6-pin RS485 terminal provided (#1 on page 7) are as follows: There is an internal short between the two A pins and between the two B pins. The instrument has no internal line termination. To terminate the line, an external resistor equal to the characteristic line impedance (typically 120) must be added at both ends of the line. Up to 32 units can be connected to the same RS485 line, with a total line length of up to 1. 2 Km using 24AWG cable. To minimize electromagnetic interferences, use shielded or twisted pair cable to connect the units. Each unit is identified by its process ID number (setup item "01"). The controller acts as a "slave" device: it only answers to commands received from a "master" device (e. g. an industrial PC) connected to the line. 30 As additional feature, the controller is also provided with two pins (5V and 0V) in order to apply the Fail Safe Open Line protection method. To avoid erroneous readings in Open-Line conditions, pullup and pull-down resistors should be connected as shown. The Fail-Safe resistors are connected only to one unit in the line, and their value depends on the application and characteristic impedance of the connection cable. The RS485 port is optoisolated from measuring circuit and power line. The analog output and RS485 port have the same ground. RS485 PROTOCOL The commands sent to the controller must have the following format: · 2-digit process ID number · 3-character command name · Parameters (variable length, may be null) · End of command (always the CR character, Hex 0D) A maximum time interval of 20 ms is allowed between two consecutive characters of a command. It is possible to send commands to change the controller settings or to simply ask information on the controller status. Following is the complete list of commands available: 31 Command CAR GET K 01 K 02 KCD KCF KCL KDS KDW KRG KST KUP MDR ECR TDR Parameter null NN null null null null null null null null null null null null null Description Request calibration data Request setup item NN Same as CFM+ +CAL keys Same as LCD+CAL+SETUP keys Same as CAL DATA key Same as CFM key Same as CAL key Same as LCD key Same as Same as key key Same as SETUP key Same as key Request firmware code Request EC reading (in control or idle mode only) Request TDS reading (HI 710 models only, available in control or idle mode only) Request measure Range (in control or idle mode only) Request temperature reading Send the 4-digit password RNG TMR PWD SET null null NNNN NNPC1C2C3C4C5 Set setup item NN to the PC1C2C3C4C5 value P=+ if value is greater than 0 P=- if value is less than 0 C1 can be 0 or 1 only C2C3C4C5 can be 0÷9 or blank (the command is not available if the controller is in setup mode) 32 Note If the controller is not in control or idle mode and the temperature reading is requested through the TMR command, the controller answers with the last acquired reading when it was in control or idle mode. After a recognized PWD command is received, the controller allows a maximum of 1 minute without receiving data, after which it locks again and a new PWD command is needed to perform password protected operations. Following are examples of commands for setup items: 1) "03 SET 22-01200<CR>" This command sets the setup item 22 (relay 2 setpoint) of a EC controller, identified by the process ID number 03, to the +12. 00 mS value. 2) "01 SET 33+005 <CR>" This command sets the setup item 33 (max. relay ON time) of a controller, identified by the process ID number 01, to 5 minutes. Once the controller has received a command, it answers with its 2-digit process ID number followed by: · ACK (Hex 06) If the controller recognizes the received command and performs the requested task; · STX (Hex 02) , Data , ETX (Hex 03) If the received command is a request of data; · NAK (Hex 15) If the received command is not recognized (e. g. the syntax is wrong); · CAN (Hex 18) If the controller cannot answer the request (e. g. the password was not sent, the controller is in setup mode, the setup item is not available in that model, etc. ) Note 33 Note The controller answers to the GET command with the same data format explained in the SET command. Following are examples of answers: 1) "03<STX>+01200<ETX>" The controller with process ID number 03 says that its current setpoint is +12. 00 mS. [. . . ] The cable used for the connection to the controller must be intact and there must be no points of broken insulation on the cable. Connectors must be perfectly clean and dry. CLEANING PROCEDURE Rinse the probe with tap water. If a more thorough cleaning is desired, remove the sleeve and clean the platinum sensors with a non-abrasive cloth or HI7061 cleaning solution. [. . . ]