Watchdog Timer - Novatech 1730 Series Reference Manual

Novatech Controls 1730 Series Diagnostics Mode Reference Manual
Once the Tx LED is flashing, use the oscilloscope to test the signal on the Tx terminal #18. If you can see
the Tx LED flashing, and the signal on the Tx terminal then move on to testing the Rx circuitry. Place the
loopback jumper between the Tx and Rx terminals to continue testing.
With the loopback on the Rx LED and the Tx LED should flash on together each second. If the Rx LED is
not flashing, use the oscilloscope to test where the signal stops working by tracing it through IC10 OP4,
then IC18 & IC19 logic gates.
25. RS485 Port
Overview: These tests are designed to check the functionality of the RS485 port by individually toggling
different port lines used by the RS485 hardware. The quickest way to confirm whether the RS-485 port
is working is to configure the port for use using runtime and try polling the device using the simple
Modbus Master PC Software available to download on the Novatech Controls website. If this suggests
that there is a problem then this diagnostic test can be used to assist in isolating the problem.
Option Up/Down: toggle different port line
Enter: no operation
By toggling each port line individually it is possible using an oscilloscope to trace the oscillating signals
one at a time through each logic gate and optical component to confirm whether they are working. The
option to toggle P6_0 is used to confirm OP1 is working. The option to toggle P6_3 is used to confirm
OP2 is working by shorting the Tx and Rx pins on IC6. To test OP3 use the automatic process for testing
the RS232 port from the previous test. If all three optocouples OP1, OP2 & OP3 are shown to be
working, replace IC6.
26. EEPROM & BBRAM
Overview: This is a non-interactive test that displays the status of the three main non-volatile storage
devices present on the transmitter. It tests whether the device is present and can be successfully read.
Option Up/Down: no operation
Enter: no operation
The first item is the iButton memory device labelled RTC located on the bottom centre of the main PCB.
This device may register as either a DS1904 or DS1994 depending on when it was commissioned. If this
device fails then the real-time clock and associated timed events may fail to work properly
The second item M24512 is a flash memory component IC29 that stores all of the device calibration and
configuration. If this device fails then the transmitter will factory reset every time it is switched on.
The third item labelled AM29F010 refers to the firmware upgrade socket. It is normal for this test to fail
unless a properly programmed upgrade EEPROM is plugged into this socket. It is also not necessary for
this socket to work for standard runtime operation; only when updating the on-board firmware.

27. Watchdog Timer

Overview: This tests the internal watchdog timer in the device. If the watchdog timer works then the
device should automatically reset approximately 200 milliseconds after pressing one of the option keys
to commence the test.
Option Up/Down: commence testing the watchdog timer
Enter: no operation
The device will reset, this is the purpose of the watchdog timer. If the device resets then this test has
passed. If the device does not reset then contact Novatech Controls to discuss options.
Document Revision 1.03 Page 15 of 16 Diagnostics Mode v1.08