T22H outputs malfunction

[ashish]

We are using T22H plc in our system.
wiring is done as per mentioned in manual.

when we power up our plc panel first time and provide input to plc, output 1,2,3,4

goes high immediately.
Now these outputs are continuously high.
we power off the whole system and power ON again but these outputs turned ON on

power ON itself, which should not happen.
Also, it does not show these outputs ON in online monitoring mode.

[support]

What do you mean by "goes high"? Do you mean voltage is raised to about 24V? That's normal because the outputs are NPN, meaning when OFF, it is internally pulled up to the power supply voltage level. When ON it is pulled down to near zero volts by the output driver.

The Output LED will not be turned ON when the output is pulled to the high voltage. It will only be turned ON when the output is pulled to the low voltage (i.e. when output is = ON).

[ashish]

outputs of controller goes ON. All 4 output LEDs are 'ON' when we power on the board.  They remain ON continuously irrespective of program condition.
There is no program condition to ON the output on power ON. These LEDs remain ON even if i OFF and ON the system.

[support]

In that case the output driver ULN2803A is probably fried. These output drivers can be damaged when a short circuit occurred which sink more than the maximum allowable current (1A peak per output).

You can replace the driver easily by removing the blown IC and replace with a new one. The driver IC is ULN2803A and you can buy from a from local electronics store or you can contact the sales person from whom you bought the PLC to get a quote.