User manual VAISALA DMP248

[. . . ] DMP248 Dewpoint Transmitter OPERATING MANUAL M210492EN-A JULY 2003 PUBLISHED BY Vaisala Oyj P. O. Box 26 FIN-00421 Helsinki Finland Phone (int. ): Fax: (+358 9) 894 91 (+358 9) 8949 2227 Visit our Internet pages at http://www. vaisala. com/ © Vaisala 2003 No part of this manual may be reproduced in any form or by any means, electronic or mechanical (including photocopying), nor may its contents be communicated to a third party without prior written permission of the copyright holder. The contents are subject to change without prior notice. _________________________________________________________________________CONTENTS Table of contents CHAPTER 1 GENERAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 SAFETY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . [. . . ] 0. 0 <cr> Press any key when ready. . . · · · T Change the temperature and again check the transmitter against the reference. Check that the reading corresponds with the reading of the reference instrument. Press any key, enter the second point value and press <cr>. : xx. x Ref2 ?yy. y <cr> VAISALA _________________________________________________________________________ 61 OPERATING MANUAL _______________________________________________________________ · The stabilization of the sensor can be monitored well by entering c <cr> instead of the reference value. Using display/keypad commands · Leave the reference instrument and the transmitter for at least 4 hours in the same space so that their temperatures have time to equalize. Remove the filter cap prior to calibration. Disconnect the security lock jumper before turning the transmitter on!Select Cali in the main menu and then T; select two-point calibration T 2 point cal. Change the temperature and again check the transmitter against the reference. Check that the reading corresponds with the reading of the reference instrument. If necessary, change the second point reading with the arrow keys and press ENT. · · · Using LED commands · Leave the reference instrument and the transmitter for at least 4 hours in the same space so that their temperatures have time to equalize. Remove the filter cap prior to calibration. Disconnect the security lock jumper before turning the transmitter on!At the first calibration point the LED on the left flashes; adjust the first point (offset) with the arrow switches to the same reading with the reference and press ENT switch. Change the temperature and again check the transmitter against the reference. · 62_____________________________________________________________________M210492EN-A CHAPTER 6 ______________________________________________ CALIBRATION AND ADJUSTMENT · · Check that the reading corresponds with the reading of the reference instrument. If necessary, adjust with the arrow switches to the correct value and press ENT. At the second calibration point the second LED from the left flashes. Calibration of the analogue outputs The analogue outputs have been calibrated at the factory and since they are very stable, calibration of the outputs should be performed only when there is reason to believe that their adjustments have changed. Using serial commands Disconnect the security lock jumper! ACAL <cr> The outputs on channels 1 and 2 are measured and the measured values (mA or V) entered as calibration coefficients. Example: both channels have 0. . . 10 V outputs (set with AMODE command); enter the voltages measured at the analogue outputs: >ACAL <cr> Ch1 U1 ( V Ch1 U2 ( V Ch2 U1 ( V Ch2 U2 ( V ) ) ) ) ?0. 123 <cr> 9. 98 <cr> 0. 120 <cr> 9. 98 <cr> Using display/keypad commands Disconnect the security lock jumper!· Connect an ammeter/voltmeter to the output of channel 1, select Cali in the main menu and Analog outputs in the Cali menu. The following is displayed (the quantity can be either mA or V): VAISALA _________________________________________________________________________ 63 OPERATING MANUAL _______________________________________________________________ · Enter the measured lower end current/voltage on channel 1. · Enter the measured upper end current/voltage on channel 1. · Connect the meter to the output of channel 2 and enter the measured lower end current/voltage on channel 2. · Enter the measured upper end current/voltage on channel 2. Using LED commands If both the analogue outputs and humidity/temperature channels are calibrated, the analogue outputs should be calibrated first. This applies only when the calibrations are done using the LED commands!· connect an ammeter/voltmeter to the analogue outputs (connector X2) Disconnect the security lock jumper!the LED on the left flashes; set the low end of channel 1 with the arrow keys and press ENT the second LED from the left flashes; set the high end of channel 1 with the arrow keys and press ENT 64_____________________________________________________________________M210492EN-A CHAPTER 6 ______________________________________________ CALIBRATION AND ADJUSTMENT · · the LED on the left flashes; set the low end of channel 2 with the arrow keys and press ENT the second LED from the left flashes; set the high end of channel 2 with the arrow keys and press ENT The analogue outputs are calibrated to ensure that outputs are correctly scaled: for example, when the output is scaled to 4. . . 20 mA, the low end of the scale is 4 mA and high end 20 mA exactly. 20 mA output is used, the output can not be adjusted to exactly 0 mA, but to 50 µA. [. . . ] If the mains power is in use, only an authorized electrician may connect the alarm unit. A readily accessible disconnect device shall be incorporated in the fixed wiring (IEC 950). For alarm output cabling, remove the plastic plug in the transmitter housing and replace it with the cable gland. Attach the grounding wire with the screw and washer to the grounding terminal on the right-hand VAISALA ________________________________________________________________________ 131 APPENDIX 7_________________________________________________________________________ side of the module if the mains power is in use. [. . . ]