NEMA 4X Modbus Scanner Indicator


The Tek-LCD 7804A is a plastic, field-mounted, 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. It can be programmed as a Modbus RTU master, slave, or snooper. The Tek-LCD 7804A is available in two upper display line configurations: 5-digit decimal display and feet & inches display with bar graph. The lower line is the same for both versions and consists of seven alphanumeric characters. Two features that really make the Tek-LCD 7804A stand out are its wide viewing angle display and SafeTouch® through-window buttons. These buttons allow the Tek-LCD 7804A to be programmed and operated through the cover window, thus eliminating the need to remove the cover in dirty or wet environments.
  • 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″ (0.03 ft)
  • Injection-Molded, IP65, NEMA 4X Enclosure
  • SafeTouch Through-Window Button Programming
  • Isolated 4-20 mA Output Option
  • Pulse Input for Rate, Total, and Grand Total
  • 13-Digit Totalizer with Total Overflow Feature
  • Backlight Standard on All Models
  • Automatic Rate, Total, and Grand Total Unit Conversions
  • Operates from -40°C to 75°C (-40°F to 167°F)
  • Data Logging Functions and Modbus Accessible Data
  • Two Isolated Pulse Outputs Standard, Up to 5 kHz
Decimal DisplayTop Display: Five Digits (0 to 99999), 0.7″ (0.05 ft) high, 7-segment, automatic lead zero blanking. Bottom Display: Seven
Characters, 0.4″ (0.03 ft) high, 14-segment, automatic lead zero blanking.
Symbols: Total, grand total, high alarm, low alarm, SafeTouch button sleep mode/disable, password lock.
Feet & Inches DisplayTop Display: 0.60″ (0.05 ft) high, 0 to 399 FT, 11 and 15/16 IN, 7-segment, programmable 1/16 or 1/8 fraction display.
Bottom Display: Seven Characters, 0.4″ (0.03 ft) high, 14-segment, 7-digits.
Tank Level Indicator: 20-segments, F (Full) and E (Empty).
Alarm Indication: High and low alarm
Backlight: White
Display Assignment Top 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
Units and tag independent for each PV, pulse input rate, total, and grand total.
*Note: On feet and inches display models, top display used only for level Modbus process variables or math channels.
BacklightWhite LED, 10 sec auto-off when battery powered. Backlight deactivated below temperature ≈ -20°C (-4°F)
Alarm IndicationFlashing display plus HI/LO (alarm) or SET indicators.
Scan and Update RateAmbient > -20°C (-4°F): 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 (-4°F): All Modbus scan, alternating units and tags, and pulse input variables update/10 seconds
Under RangeUpper Display: Decimal display flashes -9999. Level display flashes to 399 FT, 11 and 15/16 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-window 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
Password Menu OptionsThree programmable password selections can be used for the following: restrict modification of settings, prevent resetting the total or grand total without the password, or permanently lock out the ability to change or reset the grand total or any grand total related settings(making a non-resettable grand total).
Pass: Restricts modifications of programmed settings to require re-entering the password to make changes.
Pass T: Restricts the reset of total to require re-entering the password. Disables the manual mode reset contact.
Pass GT: Restricts the reset of grand total to require re-entering the password. May enable a non-resettable grand total
and permanent lockout of grand total-related settings with a specific password.
MountingMay be mounted directly to conduit. Two slotted flanges for wall mounting or NPS 1½” to 2½” or DN 0.13 ft to 0.21 ft
pipe mounting.
Display OrientationDisplay may be mounted at 90° increments up to 270° from default orientation.
Overall Dimensions5.67″ x 5.25″ x 4.18″ (0.47 ft x 0.43 ft x 0.34 ft) (W x H x D)
Weight1.65 lbs (26.4 oz, .75 kg)
Warranty 3 years parts and labor

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