Instruction Manual
Tek-LCD 7801C
www.tek-trol.com
Technology Solutions
103
3.
Modbus Inputs: Check the Timeout setting,
increase the timeout if necessary.
Display response seems slower than
normal
Ambient temperature is too cold: Consider
installing a heater with the instrument.
Display reading is unstable, it
fluctuates too much
1.
Check signal source stability
2.
Increase filter value
3.
Decrease the display refresh rate (increase time)
mA input not responding to signal
changes (value frozen)
1.
Cycle the power or
2.
Go to setup mA input and disable input channel,
then enable the input channel
3.
Check that back cover is fully
seated, and all I/O
cards are tightly fixed in place.
Display locks up or the instrument
does not respond at all
Cycle the power to reboot the microprocessor.
Settings reprogrammed, but
instrument behavior remains as
previously programmed
Cycle the power to reboot the microprocessor.
Relay and status do not respond to
signal
1.
Check if relays are in manual control mode.
2.
Check Setup menu alarm set and reset points.
Writing to Modbus Input register
failed
Check register number or register address being
used
1.
If using PLC address (Base 1) use register
number (e.g. 46701)
2.
If using Base 0 address, use register address
(e.g. 6700)
The Modbus value being read is not
correct
1.
Check the data type.
2.
Check the byte order.
3.
Confirm the units being sent by the server
Controller does not communicate
with another device.
Check baud rates and parity settings. Make sure all
serial devices have matching parameters.
Other symptoms not described above Call Technical Support for assistance.
