Explosion-Proof Modbus Scanner


The Tek-LCD 7804B is an explosion-proof, RS485 serial input Modbus® RTU scanner capable of scanning up to 16 Modbus variables and displaying them on an easy-to-read, dual-line, LCD display. This Modbus scanner can be programmed as a Modbus RTU master, slave, or snooper. The Tek-LCD 7804B is available in two upper display line configurations: 5-digit decimal display and feet & inches display with a bar graph. The lower line is the same for both versions and consists of seven alphanumeric characters. The Tek-LCD 7804B carries FM, CSA, ATEX, and IECEx approvals for use in hazardous areas. Two features that really make the Tek-LCD 7804B stand out are its wide viewing angle display and SafeTouch® through-glass buttons. These buttons allow the Tek-LCD 7804B to be programmed and operated through the glass, thus eliminating the need to remove the cover in a hazardous area.
  • Modbus® Master, Slave, or Snooper Mode
  • Scan up to 16 Modbus Process Variables
  • 5-Digit Decimal or Feet & Inches Level Display
  • On-Board Three-Wire RS-485 with Modbus
  • Independent Scaling, Tag, and Unit for Each PV
  • 7 Alphanumeric Character 0.4″ (10.2 mm) Lower Display for Process Variables, Custom Units, and Tags
  • Explosion-Proof, IP68, NEMA 4X Enclosure
  • Isolated 4-20 mA Output Option
  • Pulse Input for Rate, Total, and Grand Total
  • 13-Digit Totalizer with Total Overflow Feature
  • Password Protection
  • Two Isolated Pulse Outputs Standard, Up to 5 kHz
  • Operates from -40 °C to 75 °C
Decimal DisplayTop:Top Display: Five Digits (0 to 99999), 0.7″ (17.8 mm) high, 7-segment, automatic lead zero blanking.
Bottom Display: Seven Characters, 0.4″ (10.2 mm) high, 14-segment, automatic lead zero blanking.
Feet & Inches DisplayTop Display: 0.60″ (15.2 mm) high, 0 to 399FT, 1115/16 IN, 7-segment, programmable 1/16 or 1/8 fraction display.
Bottom Display: Seven Characters, 0.4″ (10.2 mm) high, 14-segment, 7-digits.
Display AssignmentTop and Bottom Display*: Process Variables (PV); Alternating PV and Units, Tag and PV, or Tag, PV, and Units; Pulse Input Rate,
Total, or Grand Total with Alternating Tag.
Bottom Display: All Top Display Options or Off
BacklightWhite LED, 10 sec auto-off when battery powered. Backlight deactivated below temperature ≈ -20°C
Alarm IndicationFlashing display plus HI/LO (alarm) or SET indicators.
Scan and Update RateAmbient > -20°C: Modbus PV scan rate programmable from 2 to 99 seconds per PV. Tag and units programmable for 1 to 5 second alternation. Pulse input variables update 1/second. Rate update is dependent on gate settings.
Ambient < -20°C: All Modbus scan, alternating units and tags, and pulse input variables update/10 seconds minimum.
Under RangeUpper Display: Decimal display flashes -9999
Level display flashes to 399FT 1115/16 IN
Lower Display: Flashes -999999
Over RangeUpper Display: Decimal display flashes 99999
Level display flashes to 399FT 1115/16 IN
Lower Display: Flashes 9999999
Programming MethodFour SafeTouch through-glass buttons when cover is installed. Four internal push buttons when cover is removed.
RecalibrationCalibrated at the factory to read frequency in Hz. No recalibration required.
Input Power9-30 VDC, 38 mA max. 2.2 W
EnclosureExplosion-proof die-cast aluminum with glass window, corrosion resistant epoxy coating
MountingMay be mounted directly to conduit. Two slotted flanges for wall mounting or NPS 1½” to 2½” or DN 40 to 65 mm pipe
Display OrientationDisplay may be mounted at 90° increments up to 270° from default orientation.
Overall Dimensions5.67″ x 5.24″ x 4.88″ (144 mm x 133 mm x 124 mm) (W x H x D)
Weight5.00 lbs (80 oz, 2.27 kg)

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