datel, inc., mansfield, ma 02048 (usa) ? tel: (508)339-3000, (800)233-2765 fax: (508)339-6356 ? email: sales@datel.com ? internet: www.datel.com 4-20ma current loop application board for dms-30lcd meters dms-EB-LP features ? ? ? ? ? loop-powered, no external supply required ? ? ? ? ? includes gain (span) and offset (zero) adjustments ? ? ? ? ? range and decimal point settings are dip-switch selectable ? ? ? ? ? covers hundreds of different ranges ? ? ? ? ? reliable screw-terminal connections ? ? ? ? ? low cost ordering information dms-EB-LP current loop board dms-bzl1 bezel assembly dms-bzl2 bezel assembly with sealing gasket full scale input 4ma to 20ma voltage drop 7.5v, maximum input resistance 550 ?, nominal accuracy 0.05%fs 1 count operating temperature range 0 to +60c temperature drift 100ppm/c, typical storage temperature range ?20 to +75c humidity 0 to 95%, non-condensing dimensions 2.02" (51.31mm)l x 0.83" (21.08mm)w tb1 wire size and strip length: 18 to 26 awg (solid or stranded) strip length 0.20" (5.08mm) functional specifications (t a = +25c) figure 1. dms-EB-LP schematic diagram actual size description: the dms-EB-LP was specifically designed for 4-to-20ma current-loop process-monitoring applications. the board simply mounts onto the rear of a dms- 30lcd-1-5, allowing both the application board and the meter to be powered solely from the 4-to-20ma loop input. align pin 1 of the board with pin 1 of the dms-30lcd-1-5 and simply solder the two assemblies together. features: gain (span) and offset (zero) adjustments are both performed using precision, 22-turn potentiometers. decimal point selections and range changes are all made on an eight-position dip switch featuring gold-plated contacts ? there are no cumbersome jumpers or solder gaps to contend with! connections to the loop are made via a reliable, screw-type terminal block. the only assembly tool required is a screwdriver! applications: the dms-EB-LP's design accommodates hundreds of different display reading combinations. this essentially eliminates the need to order "specials" in applications in which several different- range meters are required. oem customers should consider using datel's new dms-30lcd-4/20s which already has the dms-EB-LP soldered to a rugged dms-30lcd-1-5 digital voltmeter. technical notes dp3 dp2 dp1 ( ? ) input lo (+) input hi analog common ref. in +5v supply v ? gnd v+ cap ? cap+ r1 90.9 r4 2.21k r7 2k gain adjust c3 2.2f, 10v d2 rlz5231 c1 2.2f 10v + 2 1 4 5 3 8 u1 loop return loop input ? + 4-20ma r5 698 r2 2.94k tb1 2 1 r6 90.9 rj4 0 r9 10.5 5 6 7 8 1 2 3 4 r12 5k d1 lm4041 r10 10k c2 2.2f 10v on r8 26.7 r3 5k zero adjust boost + + 12 11 8 7 10 9 3 4 5 6 2 1 5v return sw1 ?? 12 tb1 r3 zero adjust r7 gain adjust c2 sg10 +? tb2 2 1 u1 c1 c3 d2 sw1 d1 r10 r6 r9 r8 r1 sg9 rj4 5 6 7 8 1 2 34 o n r12 www.datel.com
datel, inc. 11 cabot boulevard, mansfield, ma 02048-1151 tel: (508) 339-3000 (800) 233-2765 fax: (508) 339-6356 internet: www.datel.com e-mail: sales@datel.com data sheet fax back: (508) 261-2857 datel (uk) ltd. tadley, england tel: (01256)-880444 datel s.a.r.l. montigny le bretonneux, france tel: 01-34-60-01-01 datel gmbh m nchen, germany tel: 89-544334-0 datel kk tokyo, japan tel: 3-3779-1031, osaka tel: 6-354-2025 datel makes no representation that the use of its products in the circuits described herein, or the use of other technical info rmation contained herein, will not infringe upon existing or future patent rights. the descriptions contained herein do not imply the granting of licenses to make, use, or sell equipment constructed in accordance therewith. specifications are s ubject to change without notice. the datel logo is a registered datel, inc. trademark. ?? iso 9001 iso 9001 registered examples as shipped, the dms-EB-LP is factory calibrated to read "000" for a 4ma input and "1999" for a 20ma input but may require recalibra- tion when connected to a dms-30lcd-1-5 digital voltmeter. the following worst-case procedure assumes the dms-EB-LP is completely mis-adjusted, i.e., both potentiometers and the dip switches are randomly set. 1 . set r7 (full scale gain adjust) and r3 (zero/offset adjust) fully clockwise, roughly 22 turns, and place sw1-sw8 to off (down position). 2 . set sw1 to on (up position). see dip switch setting #3 in table 1. 3 . apply a precision 4ma input, with proper polarity, and adjust r3 until the meter's display reads "000". 4. apply a precision 20ma input and adjust r7 until the meter's display reads "1999". repeat steps 3 and 4 to make sure the adjustments do not affect one another. 5 . select the appropriate decimal point by setting sw5, sw6 or sw7 to on (dp1, dp2 or dp3 respectively). note: if a display reading other than "000" to "1999" is desired, refer to table 1 for sw1-sw4 settings. 1. desired display readings are: 4ma ="0.00" 20ma = "2.00" use dip-switch setting #1 and enable decimal point dp2 via sw6. apply 4ma and adjust r3 so the display reads "0.00". apply 20ma and adjust r7 so the display reads "2.00". 2. desired display readings are: 4ma =" ? 100" 12ma = "000" 20ma = "100" use dip-switch setting #4. apply 12ma and adjust r3 so the display reads "000". apply 20ma and adjust r7 so the display reads "100". apply 4ma and the display should read " ? 100". for these display readings, no decimal points are used. set sw5, sw6 and sw7 to off (down position). 3. desired display readings are: 4ma = "-157.5" 12ma = "00.0" 20ma = "157.5" use dip-switch setting #7 and enable decimal point dp3 via sw7. apply 12ma and adjust r3 so the display reads "000". apply 20ma and adjust r7 so the display reads "157.5". apply 4ma and the display should read " ? 157.5". 4 . desired display readings are: 4ma = ".000" 12ma = ".250" this example is not as straightforward as the previous three. notice that 12ma is exactly halfway between 4ma and 20ma. if we assume that the input could go up to 20ma, the display reading would then be: 2 x .250 or ".500". from the chart, we can now select dip-switch setting #2 and enable dp1 via sw5. apply 4ma and adjust r3 so the display reads ".000". apply 12ma and adjust r7 so the display reads ".250". operating and setup instructions table 1. dip-switch settings note: when looking up dip-switch settings in the table and the desired display readings happen to fall between two switch settings, try performing the adjustments with both settings to determine which one offers the better settability. please keep in mind that the dms-30lcd meter has an accuracy specification of 2 counts (max.). thus, it may not always be possible to obtain the exact desired display reading. display reading sw1 sw2 sw3 sw4 1. 000 to 100-300 on on on off 2. 000 to 400-600 off on off off 3. 000 to 700-1999 on off off off 4. 100 on on on off 5. 200 to 300 on on off off 6. 400 to 600 on off off off 7. 700 to 1900 off off off on dms-EB-LP 4-20ma current loop application board ds-0304a 1/98
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