neerajpuranik
Member
Dear All,
We have made the age old mistake of laying all cables (DI/DO/AI/AO/ VFD Power & Control/ DOL Power & Control) in one cable trey. I know it's a sin but now it will be hard to undone. The simplest way is to re-lay the cables properly separated by distance between Power/ Control & Signal cable treys but the plant is up & running so it will be hard to do it.
The problem I am facing is only with 05 nos of Digital inputs (24VDC). These inputs are close feedback of Pneumatic Actuator Valves. When the valve is open the open feedback is rock steady but when they are close the close feedback fluctuates on & off. Giving feedback loss alarm. On IO module the voltage is steady 23.4Volts & LED Glows full amber & there is no fluctuation but when we monitor it in PLC Program it shows the bit getting On/ Off. Rest of the plant is running fine even analog signals in which shield is grounded panel side are ok.
Is there any way or any device which can reduce the noise in the close feedback cable.
I have heard of Ferrite Cores but have not seen anyone actually using it in IO cables of PLC.
If any one of you have used them or any other device to filter noise kindly guide me.
The PLC I am using is ABB PM581 & Input Module is DI524
Regards,
Neeraj
We have made the age old mistake of laying all cables (DI/DO/AI/AO/ VFD Power & Control/ DOL Power & Control) in one cable trey. I know it's a sin but now it will be hard to undone. The simplest way is to re-lay the cables properly separated by distance between Power/ Control & Signal cable treys but the plant is up & running so it will be hard to do it.
The problem I am facing is only with 05 nos of Digital inputs (24VDC). These inputs are close feedback of Pneumatic Actuator Valves. When the valve is open the open feedback is rock steady but when they are close the close feedback fluctuates on & off. Giving feedback loss alarm. On IO module the voltage is steady 23.4Volts & LED Glows full amber & there is no fluctuation but when we monitor it in PLC Program it shows the bit getting On/ Off. Rest of the plant is running fine even analog signals in which shield is grounded panel side are ok.
Is there any way or any device which can reduce the noise in the close feedback cable.
I have heard of Ferrite Cores but have not seen anyone actually using it in IO cables of PLC.
If any one of you have used them or any other device to filter noise kindly guide me.
The PLC I am using is ABB PM581 & Input Module is DI524
Regards,
Neeraj