Jandel RM3 operating instructions

Transcription

1 Jandel RM3 operating instructions Features Integrated Custom Membrane and Keypad LCD Display 16 x 2 Numeric Keypad for entry of selected current User programmable set currents selected by pressing one of several program buttons Forward Button with LED Reverse Button with LED Standby Automatic Compliance setting Send Button for storing the current measurement for output via the RS232 RS 232 output of current set, voltage reading, calculated sheet resistance Voltage / Ω/ button to choose whether volts or Ω/ are displayed. Self test against external precision resistor, 100Ω Set Currents up to mA and down to 10nA. Compliance voltage up to 40V Accuracy of the instrument within 1% across whole range. Attractive ABS case from the same series as the RM2 Beeper to acknowledge key presses.

2 Operation The unit powers up in Standby. The green lights at POWER and STBY are illuminated and the Display reads Jandel RM3 V1.3 STANDBY H Setting the Current Enter the required current on the numeric keypad press ma, ua, na. The unit will display the set current in the top line of the display. Press forward, reverse, the LCD Display will change, to display voltage or calculated impedance in the second line of the display. If you choose forward or reverse then subsequently pressing standby will cause current to fall to zero and display will show the "standby message. Error Messages During attempting a reading, several error messages are possible instead of a reading. Out of Range indicates that the reading exceeds the maximum input of the in-built DVM. Reduce the current or the sensitivity of the internal DVM, or use an external DVM Contact Limit indicates the automatic compliance voltage has been reached due to contact resistance or too much current, try reducing the current. Illegal current indicates that the set current is outside the normal 10nA to mA range. Set a new current Calibration Error indicates an error in the factory calibration (see below) Calibration/Self Calibration The overall calibration of the current source is carried by potentiometer adjustment. The internal DVM has no calibration potentiometers, its calibration is carried out in the factory. This can be recalibrated if required, if the factory calibration factor is outside certain limits or has become corrupted Calibration Error is displayed. A separate internal DVM calibration occurs at power up. It recalibrates against an internal reference at power up and when changing from Low to High sensitivity. The zeroing of the DVM also occurs at this time. The meter zero can be forced at any time by pressing the Zero button. The Zero button is used to minimize offsets causing differences between forward and reverse readings.

3 Preset Currents In order to ease operation for repeated measurements, four programmable presets are available to the user. Pressing the preset button will load the preset current In order to program the presets, with a new value enter the required set current. Press and hold the relevant, "preset" button several seconds until a beep is heard. The preset button current is then programmed. RS232/USB and Data output Whilst the USB is powered by connecting to a PC etc the USB takes control of the external communications and all data sent will be sent via USB. Voltage / Sheet Resistance The display can be the voltage measured or the calculated sheet resistance. This can be selected by the Ω/ button. The selection will remain until selected again. When powered off the last setting of this option will be remembered. The display will use the most suitable units for the value measured mohms/square, ohms/square or Kohms/square Compliance Voltage The compliance voltage is automatic, and is used to limit the Power dissipated in the sample under test. For currents under 1 ma the voltage applied is the maximum 40v. For currents of 1mA and above the voltage applied to the source is limited to an absolute maximum of 25 volts. Above 10mA the voltage is limited so as no more than 0.5W could possibly be dissipated in the sample so at 50mA the compliance voltage is limited to 10V, and at mA it is limited to 5Volts. Extra caution is required on the use of currents over 10mA to avoid damaging the samples. Standby The Standby button is used to pause the flow of current through a sample. When in Standby the selected current is displayed. The equipment may be set to revert automatically to standby. In this case the equipment returns to standby after 10 seconds.

4 To use this option the user must hold the Standby button until a beep is heard. The setting of the automatic standby option is stored when the equipment is powered down. The option to auto standby after 10 seconds can be turned off in the same way as it was turned on. When powered up the unit will come on in standby mode so that no current flows through the sample. Summary of Buttons Numeric Keypad 0-9 also point "." and "del" to delete set current FWD - Forward REV - Reverse STBY - Standby ZERO - forces the DVM to make an offset calibration SEND - writes to the external PC, via the chosen "serial interface" the set current and the reading. Sens - changes the sensitivity of the DVM from Low to High Ω/ - voltage / sheet resistance Preset 1-4 preset buttons for set currents Test - if an external 100Ω load resistor is connected Remote Control Remote control is available via RS232 or USB, (but only one or the other). The unit automatically detects the presence of the USB. If connected, the USB takes precedence. Command is via simple single character commands. Data Output data is in the form of coma separated variables (CSV). Sending an "O" to the RM3 causes it to Send or Output the set Current and the Voltage Reading displayed at that time. USB Port utilize an FTDI device, and drivers are available on the web site: or (the URL is case sensitive) Once the driver is correctly installed, connecting the RM3 will add a comport to your PC, and you can configure your PC to control or receive data over the port. Instructions for loading of the driver are included within the driver zip folder. This kind of device is commonly used in RS232 to UPB adaptor cables. Software used to control or receive measurement data from the PC should be identical whether the port utilizes the USB or RS232 (only the COM number will be different). The com port number will vary depending on your PC configuration. For laptops the

5 com port is usually 2 and for desktops without a modem it is often 3, but these are only a general guide and you will need to determine this yourself. Whether using the RS232 or USB, the com port settings are 9600 baud, 8 bit, no parity, 1 stop bit. Hardware and X on/off handshaking are not used. A small 32 character buffer is present on the RM3 to queue commands sent by the RS232. Try not to send too many at one time. It should be possible to build and send small macros to set the current and zero the reading etc from the PC. Data output from the RM3 is in CSV format. This is the most basic format understood by databases and spreadsheets. Some means of capturing the data into a file on the PC will need to be used. AT the most basic level, data can be captured in hyperterminal. Save it as a text file, change the files extensions to.csv, and it can then be opened in excel. Even without special software, using hyperterminal it is possible to control the RM3 and cause it to output data remotely. The remote control commands simply mimic the operation of the keypad. They are: 1 to 9 and. to set the current. Terminate in m, u, or n m for ma u for ua n for na e will erase the current setting. If entering a current sending. f sets the forward current r sets the reverse current s puts the RM3 in standy mode z zeros the reading h sets high resistivity mode (either 2 or more decimal places max +/- 130mV) l low sensitivity (1 decimal places max +/- 1300mv) a first preset current b second present current c third preset current d fourth present current q changes display from ohms/sq to mv o output data through the serial or USB port 5 Pin Din Plug 1. Current source RED 2. Earth 3. Current source BLUE 4. DVM GREEN 5. DVM - YELLOW Screen is earth