User manual HANNA INSTRUMENTS HI 504

[. . . ] HI 504 Panel-mounted, Microprocessor-based pH/ORP Process Controller Instruction Manual TABLE OF CONTENTS WARRANTY . 103 ELECTRODE CONDITIONING AND MAINTENANCE . 113 3 WARRANTY All Hanna Instruments meters are guaranteed for two years (sensors, electrodes and probes for six months) against defects in workmanship and materials when used for their intended purpose and maintained according to instructions. This warranty is limited to repair or replacement free of charge. [. . . ] 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. The RS485 can connect up to 31 HI 504 on the same physical network. All the units are slave devices and are monitored and controlled by a single master station (typically an industrial PLC or PC). Each HI 504 unit is identified by its Process ID number, included in the 00 to 99 interval, which corresponds to the Process ID configured through the setup item G. 11. (If the instrument does not recognize the address within the command string, then it discards all the following bytes). As additional feature, the controller is also provided with two pins (5V and GND) in order to apply the Fail Safe Open Line protection method. To avoid erroneous readings in Open59 Line conditions, pull-up 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 GND pin of the interface connector and all the interface signals are optoisolated from the ground of the instrument, the electrode and the temperature sensor. Before connecting the meter to the computer, consult the computer manual. The process controller can only work as a slave component. In other words it can work as a remote terminal equipment answering to the commands only. RS485 PROTOCOL FOR HI 504 Commands are composed of four parts: addresses, command identifier, parameter, end of command. Some commands are used when the master is requesting information from the controller, other when the master wants to set a parameter in the process memory (RAM or EEPROM). The end of commands corresponds to the CR char (0x0d). The master software must send the command string with a maximum delay of 20ms between each character. The program on the master must not allow setting commands other than keyboard or cleaning start/stop commands if the general password has not been entered. After the general password recognition through the "PWD" command, a 1minute time-out is let before the process meter locks again, i. e. if the PC program waits for more than 1 minute between two subsequent setting commands, the second one is not fulfilled and the "PWD" command must be issued again. 60 Following is the complete list of commands available: Command NNMDR NNHOP NNSNR NNSTS Parameter not available not available not available not available Remarks Requests firmware code (always available) Requests hardware options Requests hardware identifier (always available) Requests instrument status (relays, LEDs, configuration change flag, etc. ) Requests last pH reading (instrument configured for pH) Requests last mV reading (always available) Requests temperature reading (instrument configured for pH) Requests all last calibration data (always available) Requests setup item C. NN. Use the NNSNR command if hardware identifier is needed. (NNGET command is answered with "<ProcessID><CAN>" for the hardware identifier) Sends the general password (always available) NNPHR NNMVR NNTMR NNCAR NNGET not available not available not available not available CNN NNPWD NNSET C1C2C3C4 CNNP1P2C1C2C3C4 Sets setup item C. NN with parameter P1P2C1C2C3C4(*) (not available in setup mode) not available Requests event log file (available in idle, event scrolling or last calibration data scrolling mode w/control OFF) NNEVF 61 Command NNEVN NNAER NNCLS NNCLP NNHLD NNKDS NNKCD NNKUP NNKRG NNKST NNKCL NNKDW NNKCF NNK 02 Parameter not available not available not available not available not available null null null null null null null null null Remarks Requests new events (always available) Requests active errors (always available) To start advanced cleaning (always available) To abort cleaning (always available) To enter/exit the hold mode (always available; pwd required) Same as LCD key Same as CAL DATA key Same as Same as key key Same as SETUP key Same as CAL key Same as key Same as CFM key Same as LCD+CAL+SETUP keys (*) C1C2C3C4 are ASCII chars corresponding to the setup item content; P1P2 are two additional bytes used for sign and half digit as follows: P1 P1 P2 P2 = = = = + 0 1 if>0 if<0 if most significant digit is not used if most significant digit is used When an item is shorter than 4 digits the Ci characters are filled with blanks. 62 Following are examples for setup item format: · item C. 32, maximum relay ON time: parameter value = 15, format = "+015", where indicates a blank; · item C. 21, setpoint 2 value while in ORP mode: parameter value = -1200 mV, format = "-01200"; · item G. 01, temperature compensation: parameter value = "AtC", format = "+0*AtC". For all items with a fixed set of choices, blank spaces on the left of the value displayed are replaced with "*" (as many "*" characters are needed to reach the maximum string length, which is for example 3 for item C. 57). Blanks must be put on the tail for all items in order to have always a total length of 6 characters (see the setup table). [. . . ] That protects against power failures and interruptions of the alarm relay external wires. HYSTERESIS Interval that must be passed over by the controlled magnitude in the opposite direction after having activated a relay, before deactivating it, in order to avoid uninterrupted activation/deactivation of the relay. IN-LINE CLEANING Automatic procedure to stop control, clean the electrode and then activate control again. NIST National Institute of Standards and Technology. [. . . ]