DRB-Pulse Switch Troubleshooting

Common Pulse Switch Errors

• The tunnel equipment keeps turning on (or off) too early (or too late), and it gets worse the farther down the tunnel the car goes.  When I check TunnelWatch, there is a message scrolling across the bottom of the screen (or in the Exceptions Log) that says “No Pulse: Sim Pulse” or “Simulated Pulse On”.  I turn the Simulated Pulse off, but it keeps coming back.

• The conveyor stops while I’m washing cars, and TunnelWatch has a message scrolling across the bottom of the screen (or in the Exceptions Log)  that says “No Pulse: Conv. Stop”.  I restart the conveyor, and everything is OK for a while, but it keeps happening.

• The tunnel equipment turns on (or off) too early (or too late) sometimes.  When that happens, the problem does not get any worse the farther down the tunnel the car goes, and the next car is fine.  When I check TunnelWatch, there is a message scrolling across the bottom of the screen (or in the Exceptions Log) that says “Pulse Sw. Intermitnt”, or “Roller Jammed Convr.” and the Lost Pulses counter keeps going up.

• When I look at the Pulse Input in the Interface Station or Tunnel Control Station, it appears to be blinking steadily and regularly.  However, when I look at the TunnelWatch screen, the pulse stays on all the time.

• I sometimes see “Vehicle was too long” or “Vehicle was too short” scrolling across the bottom of the screen (or in the Exceptions Log) in addition to one or more of the above symptoms.

Notes:

This document is not intended as a comprehensive troubleshooting guide for your pulse switch hardware and wiring.  Consult your facility technician for further assistance troubleshooting the pulse wiring or hardware.

Using Simulated Pulse

In any situation revolving around pulse related issues it is best to get the line rolling again and washing cars by temporarily switching to Simulated Pulse.  Oftentimes the TW system will automatically switch to Sim Pulse so check the configuration to make sure it matches the intended optimal Sim Pulse conveyor speed as listed on your TCS sheet.

1. Turn on Pulse Switch Simulation

a. Navigate to the Operations tab of TunnelWatch

b. Set Pulse Switch Simulation to 'On' if it isn't already

c. Set the conveyor speed to match the desired speed the tunnel normally operates at as indicated on your TCS guide sheet in the tunnel room hanging near your TCS.

i. If you cannot find the sheet you can also go to the 'Reports' menu, select 'Daily Reports' and select a recent date where the tunnel operated without issue - in the top right the Conveyor Speed will give you the last properly working average speed of the conveyor, use this to input the desired conveyor speed on the operations screen in the Pulse Switch Simulation section.

ii. If services are turning on too late, press the + (plus) key to speed up the simulated pulse.

iii. If services are turning on too soon, press the - (minus) key to slow down the simulated pulse.

iv. After each adjustment of the simulated pulse speed, run a test car to see if more adjustment is needed.  Typically, the timing of the final rinse arch is a good indication of how close you are.

2. Check the Minimum and Maximum Pulse Time settings for the conveyor.

a. Run the conveyor at the fastest speed you expect to run.  

b. Time the pulse by physically observing the pulse switch and using a timer with at least 1/10th of a second accuracy.  DO NOT use the Pulse Input in your Interface Station or Tunnel Control Station, or the TunnelWatch screen(s).  These may result in inaccurate measurements.  If the pulse is too fast to easily time a single pulse (you should be shooting for 1/10th of a second accuracy), try starting the timer when a pulse comes around, count ten more pulses, and stop the timer.  (That is, start the timer on pulse 0, and stop it on pulse 10.)

c. Divide the resulting time in seconds by ten.  This is the average pulse time at the fastest conveyor speed.  

d. Divide this measurement by 2 to get the Minimum Pulse Time.  

e. Slow the conveyor down to the slowest speed you expect to run.  

f. Time the pulse again; this is your average pulse time at the slowest conveyor speed.  

g. Multiply this measurement by 4 to get the Maximum Pulse Time.

h. Enter the resulting measurements in TunnelWatch by going into Modify Setup, then Tunnel Related Inputs.  Change the Minimum and Maximum Pulse Times to the figures you calculated.

3. Check the Pulse Input at the Tunnel Control Station.  Ideally, this would be done so that the symptoms happen while you are observing the Pulse Input.

a. With the conveyor running, the pulse input should flash steadily and regularly.  

b. If the pulse input does not come on at all:

i. Disconnect both wires to the input.

ii. Use a small piece of wire to short the screw terminals for the input together.  A paper clip will do since the inputs are only 24v and do not present an electrical shock hazard.

iii. If the pulse input comes on, then the problem is most likely in the pulse switch, its adjustment, or the wiring.  Proceed to step 4.

iv. If the pulse input on the operations screen does not come on, try moving to another input.

v. If the problem still persists, replace the TCS Input card.

c. If the pulse input stays on constantly:

i. Disconnect both wires to the input.

ii. If the pulse input goes out, then the problem is most likely in the pulse switch, its adjustment, or the wiring.  Proceed to step 4.

iii. If the problem persists, try moving to another input.

iv. If the problem still persists, replace the TCS Input card.

d. If the pulse is irregular, e.g. longer pauses between some flashes, periods where the indicator stays on longer than others, etc, then the problem is most likely in the pulse switch, its adjustment, or the wiring.  Proceed to step 4.

4. Check the pulse switch input indicator in TunnelWatch on the operations screen.  Ideally, this would be done so that the symptoms happen while you are observing the Pulse Input.

a. With the conveyor running, the pulse input (typically A>) should flash steadily and regularly.

b. If the pulse input does not come on at all, but the input is flashing normally in the Tunnel Control Station:

i. Disconnect and reconnect both ends of the cable.  Make sure the connections are snug and the retaining screws are tight.  

ii. If the pulse input on the ALT-S screen does not come on, try moving to another input.

iii. If the problem still persists, replace the TCS Input card.

c. If the pulse input stays on constantly, but the input is flashing normally in the Tunnel Control Station:

i. Disconnect both wires to the input.

ii. If the pulse input on the operations screen goes out, then the problem is voltage leakage from the pulse switch or a partial wiring short.  After checking the pulse switch wiring, either replace the pulse switch or install an intermediate relay between the pulse switch and the input.

iii. If the pulse input on the operations screen does not go out, try performing a TW Reset.

iv. If the problem persists, try moving to another input.

v. If the problem still persists, replace the TCS Input card.

d. If the pulse is irregular, e.g. longer pauses between some flashes, periods where the indicator stays on longer than others, etc, but the input is flashing normally in the Tunnel Control Station:

i. Perform a TW Reset.

ii. If the problem persists, try moving to another input.

iii. If the problem still persists, replace the TCS Input card.

5. Check the Pulse Input setup.

a. If the system seems to periodically miss a pulse, especially when under heavy load (like when doing backups), then the pulse input may be too short for TunnelWatch to pick up consistently.  Check the following:

i. From TunnelWatch select 'Setup' menu.

ii. Select Tunnel Related Inputs.

iii. On the Pulse Switch line, check the Debounce field.  Change it to 0.0 seconds.

• If the field is already 0.0 seconds, then consider increasing the amount of time the pulse switch is activated.  If using a bolt head, you might attach a large washer to it, etc.

6. Check the physical adjustment of the pulse switch.  

a. Make sure the gap between the head of the pulse switch and the magnets/bolts/paddles that pass by it is as small as is reasonable possible to ensure a good read by the pulse switch.

b. Make sure there is no debris that would interfere with the functioning of the pulse switch.

c. Make sure the pulse switch and magnets/bolts/paddles are relatively clean, dry, and free from magnetic filings.

7. Check the pulse switch wiring (pulse switch type dependent)

a. Visually inspect the wiring from the pulse switch.  Be alert for any cracked or otherwise damaged insulation, verify any slices and connections, etc, and replace or repair as needed.

b. Disconnect the wires from the pulse switch and from the pulse switch input, and check for continuity between the wires.  

c. If there is continuity between the two wires, replace the wiring.

d. Short the two wires together at one end, and check for continuity between the wires at the other end.

e. If there is not continuity through the wires, replace the wiring.

8. Replace the pulse switch with a new pulse switch.