This will be a bit long-winded, but it was a good learning experience and may be helpful to someone else...
To guard the exit of an automatic shrink-wrapper, we installed a set of light curtains and a light curtain controller (http://www.automationdirect.com/adc/Shopping/Catalog/Safety/Safety_Relay_Modules/Light_Curtain_-a-_Safety_Mat_Controllers/BH5902-22-01MF2-61) from Automation Direct. The documentation provided with the hardware was sketchy, but the on-line material was decent. We set up the components on the workbench for testing purposes. To eliminate the need to set up four muting sensors, we just used four N/C switches.
After connecting the components, setting the dials to the proper position and lining up the light curtains, everything worked as expected. If we depressed the switch representing MS1 and then the one for MS2, the light curtain was muted. Moving to the final position should be easy, right? Not!
Everything was set up in the wrapper control panel, but the controller would fault as soon as MS2 was blocked. Wiring was double and triple-checked and was found to be correct. Thinking the solid-state relays in the photo-switches were and issue, we replaced them temporarily with the NC switches used on the bench - same results.
Stumped, we took everything back into the shop and re-connected. It worked.
Back at the wrapper, we re-installed everything and... it didn't work. Same symptom.
Thinking the controller may be intermittent, we replaced it with a spare , but it still didn't work.
The wrapper is in a refrigerated milk storage room, so we thought perhaps the cabinet was too cold (specs call for 0-50C - we were at 3-4C), so we temporarily installed space heater. No luck
We used the original controller and re-connected everything in the shop. It worked, so we transferred every connection to the spare controller still in the cabinet one wire at a time. Fired it up and it didn't work.
Back to the manual (http://www.automationdirect.com/static/manuals/safetyrelays/bh5902_01mf2.pdf), I noticed that the MIN current from M1 & M2 had to be at least 25mA with active lamp. Thinking that perhaps the LED pilot lights we installed weren't drawing enough, I connected a second LED in parallel with the one installed in the cabinet cover. Muting now worked. Relieved, I decided to replace the second scabbed-on LED with a resistor. As I was loosening the connection screw on the original LED, I noticed the tag - 120VAC. It should have been 24VDC. The LED had too much resistance to allow 25mA to flow with the 24VDC control power from the controller! That was a whole day wasted, but a great learning experience.
To guard the exit of an automatic shrink-wrapper, we installed a set of light curtains and a light curtain controller (http://www.automationdirect.com/adc/Shopping/Catalog/Safety/Safety_Relay_Modules/Light_Curtain_-a-_Safety_Mat_Controllers/BH5902-22-01MF2-61) from Automation Direct. The documentation provided with the hardware was sketchy, but the on-line material was decent. We set up the components on the workbench for testing purposes. To eliminate the need to set up four muting sensors, we just used four N/C switches.
After connecting the components, setting the dials to the proper position and lining up the light curtains, everything worked as expected. If we depressed the switch representing MS1 and then the one for MS2, the light curtain was muted. Moving to the final position should be easy, right? Not!
Everything was set up in the wrapper control panel, but the controller would fault as soon as MS2 was blocked. Wiring was double and triple-checked and was found to be correct. Thinking the solid-state relays in the photo-switches were and issue, we replaced them temporarily with the NC switches used on the bench - same results.
Stumped, we took everything back into the shop and re-connected. It worked.
Back at the wrapper, we re-installed everything and... it didn't work. Same symptom.
Thinking the controller may be intermittent, we replaced it with a spare , but it still didn't work.
The wrapper is in a refrigerated milk storage room, so we thought perhaps the cabinet was too cold (specs call for 0-50C - we were at 3-4C), so we temporarily installed space heater. No luck
We used the original controller and re-connected everything in the shop. It worked, so we transferred every connection to the spare controller still in the cabinet one wire at a time. Fired it up and it didn't work.
Back to the manual (http://www.automationdirect.com/static/manuals/safetyrelays/bh5902_01mf2.pdf), I noticed that the MIN current from M1 & M2 had to be at least 25mA with active lamp. Thinking that perhaps the LED pilot lights we installed weren't drawing enough, I connected a second LED in parallel with the one installed in the cabinet cover. Muting now worked. Relieved, I decided to replace the second scabbed-on LED with a resistor. As I was loosening the connection screw on the original LED, I noticed the tag - 120VAC. It should have been 24VDC. The LED had too much resistance to allow 25mA to flow with the 24VDC control power from the controller! That was a whole day wasted, but a great learning experience.
