DSD-36 - Double Sheet Detector Complete Unit Double Sheet Detector

DSD-36 Double Sheet Detector

Features:

• Detects the thickness of ferrous metals on the face of the sensor using pulsed electromagnetic detection.
• Permits double sheet/blank detection with minimal magnetic attraction of the sheet.
• Controller, Sensor, Mounting Bracket, and Cable sold separately.
• Can detect sheets with min thickness of .25mm to a max of 2.3mm.
• Standard SAS mounting arm mounts to standard clamps.

DSD-36 Control module

The DSD-36 control module allows fast and easy setup and for diagnosis of system errors or problems. Calibration is achieved through the simple press of a push-button switch or external +24V signal. Faults are reported through different flash patterns on the green NO DOUBLE and yellow DOUBLE indicators. When the unit first powers up, the two indicators flash alternately as it calibrates the Sensor.

Features:

• +18 to +36VDC operation (nominal +24VDC.) 1A
• Form C relay output providing normally open and normally closed contacts
• Latching "DOUBLE" relay that is cleared by a high signal on the RESET input.
• LED indicators report the gage states of NO DOUBLE and DOUBLE.
• Automatic setup of system gain and operating parameters.
• Simple push-button calibration.
• Non-volatile memory that retains all calibration parameters even when power is removed.
• Sensor fault detection and reporting via the two front panel indicators.
• External CAL terminal for use by a remotely-located Calibrate switch or PLC output.
• METAL PRESENT output to verify the sheet has fed properly

DSD-36 Sensor

The sensor is potted and completely sealed. The sensors do not respond to small amounts of fine metal filings, oil or dirt. Each sensor has a proximity detector that reports METAL PRESENT and is activated when metal is within 2mm (0.08") of the sensor face. Therefore, the sensor must be kept at least 2mm from the surface of the metal if a thickness reading is not desired.

Features:

• The DSD-36 sensor works for sheet thicknesses from 0.25 – 2.3mm.

DSD-36 Spring Loaded Mounting Bracket

The spring loaded mounting bracket protects the sensor by adding compliance to the sensor mounting. It also accommodates minor flatness irregularities. The mounting shaft allows for the bracket to be mounted to SAS standard clamps and profile system.

Features:

• Guided vertical compliance as well as angular compliance.
• Standard SAS mounting arm.

Installation:

DSD-36 Control module:

The controller is designed to mount on the back panel of an electrical enclosure or robot cabinet using the four 4.5mm mounting slots at the edges of the enclosure (see figure 1). Insure that the mounting screws make good electrical contact between the module housing and a well-grounded control enclosure back panel. Avoid mounting locations with excessive heat and vibration.

DSD-36 Sensor:

To take a thickness reading, the sensor must be mounted so that the sheet is in contact with the sensor face. Each sensor has a proximity detector that detects when metal is within 2mm (0.08") of the sensor face. Therefore, if a thickness reading is not desired, the sensor must be kept at least 2mm from the surface of the metal. The face of the sensor is made of steel and will last for many years of operation when used in conjunction with the spring loaded mounting bracket.

Figure 1.

Electrical Wiring (see Figure 2a and 2b):

All wiring for the DSD-36 control module connects to removable terminal blocks at the bottom of the control enclosure.

1. Connect +18 to +36VDC to the terminals labeled +24V and COM on the left of terminal block TB1.

2. For optimum noise immunity run the shielded cable from the sensor to the board in conduit without AC or high current wiring. The sensor is connected to terminals on the rightmost terminal block TB2, labeled with the colors of the wires in the cable. Connect the shield lead (drain wire) from the sensor cable to the terminal labeled SHIELD. If a splice is made between the controller and the sensor, do not leave the sensor unshielded for more than 20 to 30 mm.

3. Connections to the control circuit of the robot are made through the form C output relay on TB1. This relay is energized in the NO DOUBLE condition as a fail-safe feature and is shown on the cover of the controller in the de-energized, DOUBLE, position. If power is lost to the controller, or if there is a DOUBLE metal condition, the relay de-energizes, opening the NO DOUBLE contact across TB1-4 and TB1-5 and closing the DOUBLE contacts across TB1- 5 and TB1-6.

4. The output relay may be operated in a Follower Mode or in a Latched Mode, depending upon the voltage applied to the RESET terminal on TB1. In the Follower Mode, the relay de-energizes when a DOUBLE is detected and re-energizes when the DOUBLE is removed. In the Latched Mode, the relay de-energizes when a DOUBLE is detected and will remain de-energized until the RESET terminal is momentarily taken to a high logic level greater than +12V and no more than +30VDC.

1. To operate the output in the Follower Mode, connect the RESET terminal on TB1 to a voltage between +12VDC and +30VDC. When a DOUBLE condition occurs, the relay drops out, closing contacts 5 and 6 on TB1, and the DOUBLE indicator comes on. When the DOUBLE metal condition is removed, the relay returns to the normally energized condition, the amber DOUBLE indicator goes out and the green NO DOUBLE indicator turns on. The Follower Mode is normally selected to control the operation when the DOUBLE condition is automatically removed or when the control module is wired into the stop circuit of a robot with a manual restart circuit.
2. To operate the output in a Latched Mode, leave the RESET terminal on TB1 open. In this mode, when a DOUBLE condition occurs, the relay drops out and the DOUBLE indicator comes on. After the DOUBLE condition is corrected, the DOUBLE indicator goes off and the NO DOUBLE indicator comes on. The RESET contact must be momentarily connected to a high logic level to bring the relay back to the NO DOUBLE state.

Figure 2a.

View from back of Sensor
Figure 2b.

Inputs and Controls:

The primary control of the control module is the CALIBRATE push-button switch on the front panel. Use of this switch is described below under CALIBRATION. The control module has two logic inputs labeled CAL and RESET. The CAL input parallels the function of the CALIBRATE push-button on the front panel, allowing the calibration function to be performed through high logic level, greater than +12VDC and less than +30VDC, from a remotely-located switch wired to this input. The RESET input controls the latching of the relay as described in item 5b of the Electrical Wiring section above.

Both the CAL and RESET inputs are activated when a high logic level, greater than +12VDC, is present.

Outputs:

The control module outputs include a form C relay for reporting a DOUBLE condition and a dc logic output for reporting METAL PRESENT in front of the sensor.

The logic output is labeled the METAL PRESENT output since it provides an indication that metal is present in front of the sensor. The intent of this output is to signal that a sheet did feed. This output provides a dc sourcing signal that switches between zero volts and 24 volts, delivering up to 50 mA.

The METAL PRESENT output is near zero volts when there is nothing in front of the sensor and is High, sourcing near +24 volts, when metal is present in front of the sensor.

Indicators:

The function of the indicators and controls on the control module are described in the following paragraphs:

1. The amber DOUBLE indicator is ON whenever the metal thickness is closer to the calibrated value for double thickness than to the calibrated value for single thickness.
2. The green NO DOUBLE indicator is ON whenever the metal thickness is closer to the calibrated single thickness value than to the calibrated double thickness value.

Through various flashing patterns, these indicators also provide information regarding system mode (calibrate vs. operate), firmware version number, and error conditions. Reading firmware version is described later in this document. All other flash patterns can be interpreted as follows:

• Fast Alternate flashing of amber and green indicates busy such as during initialization after power-up.
• Slow Alternate flashing of amber and green indicates an error condition. The reasons are various such as calibration sample too thick, sample too thin, too little difference between double and single when performing a two point calibration. There is a 30 second time out after an error, after which the unit reverts to the last good calibration.
• Green flashing, amber off - awaiting single sample for calibration.
• Amber flashing, green off - awaiting push-button press for calibration on double.
• Green flashing, amber on - sensor error. Sensor may not be connected, sensor wire broken, or sensor may be defective. To recover after the sensor error, power down and back up.

Calibration:

The detector may be calibrated via the CALIBRATE push-button switch on the front cover or remotely by supplying a positive voltage greater than +12V and less than +30V to the CAL terminal on the right terminal block, TB2-4. If you do not have external power for the Active High CALIBRATE input, +28VDC is available from TB2-9 (see Figure 4 at the end of this manual).

The control module offers two modes of calibration:

1. Calibrate on single nominal thickness (single sample teach).

2. Calibrate on single and double thickness (two sample teach).

Normally, where double thickness discrimination is required, the control module can be calibrated on a single thickness of the material to be monitored (one press of the CALIBRATE push button). If changes in the metal thickness need to be monitored (for example a 10% increase in the normal metal thickness), the control module may be calibrated on two different thickness samples of the same material (two presses of the CALIBRATE pushbutton within one second), which allows the threshold to be set between the two calibration points.

Calibration on Single Thickness Only:

Calibration on single thickness is selected when the CALIBRATE pushbutton in pressed once during any one-second period. If the sensor is not on metal when the CALIBRATE pushbutton is pressed, the green NO DOUBLE LED will begin flashing indicating that the control module is waiting to be calibrated on the single thickness.

Then, when a single sheet of metal to be gauged is pressed against the sensor face, the proximity detector will cause the control module to automatically take a reading of the metal and perform a calibration. During calibration on the single thickness, the green NO DOUBLE indicator flashes and the amber DOUBLE indicator is off.

If the sensor is on metal when the CALIBRATE pushbutton is pressed, the calibration is immediately made.

If the calibration on the single is successful, the green indicator stops flashing and remains solidly on.

If the calibration is not successful, the indicators flash alternately to indicate an error condition. To recover from an error condition, after fixing the problem that caused the error, press the CAL pushbutton again to initiate another calibration cycle. The unit will automatically recover after a 30 second timeout and revert to the previous good calibration point.

If there is an error, make sure that the sheet is solidly against the sensor when calibrating and that the sheet thickness does not exceed the sensor specification. If these concerns seem to check out, re-try the calibration. Alternatively, retry the calibration by calibrating on single and double thickness as described below. If difficulties persist, call SAS for technical assistance.

NOTE: After calibrating, always verify calibration by placing a double thickness on the face of the sensor. The control module should indicate a double.

Calibration on two samples, Both Single thickness and Double thickness:

Calibration on both single and double thickness is selected by pressing the CALIBRATE pushbutton twice within any one-second period. If the sensor has no metal on the face of the sensor the green NO DOUBLE LED will begin to flash indicating that the control module is waiting to calibrate on the single thickness.

Then, place a single thickness of material against the sensor face and the control module will automatically take a reading of the metal thickness and will perform a calibration. During calibration on the single thickness, the green, NO DOUBLE, indicator flashes and the amber, DOUBLE, indicator is off.

When the unit completes the calibration on the single thickness and the unit is ready for the double thickness, the green indicator turns off and the amber indicator flashes. Place a sample of thicker material or two samples of the single material against the sensor face and press the CALIBRATE pushbutton again. If calibration is successful, the amber indicator stops flashing and remains solidly on and the green indicator is off until the material at the sensor face is removed.

If the calibration is not successful, the indicators flash alternately to indicate an error condition. To recover from an error condition, after fixing the problem that caused the error, try initiating another calibration sequence by pressing the CAL pushbutton again twice within a one second period. The causes for unsuccessful calibration can be many, including too little difference in thickness between the thin and thick material, poor sensor contact, wrong sensor model for the material, etc.

NOTE: After calibrating, always verify calibration by placing a double thickness on the face of the sensor. The control module should indicate a double.

Firmware Version:

From time to time, as improvements are made to SAS products, the firmware controlling the units is revised. When setting a unit up or troubleshooting it may be necessary to determine the version number for the firmware installed in your unit. The version numbers begin with 1.0 and are incremented either by tenths (1.1, 1.2, etc.) for small revisions or by the integer digit (1.0, 2.0, etc.) for more significant revisions.

To determine the version of the firmware running in your unit, simply hold the CALIBRATE push button in as power is applied to the unit. Then release the CALIBRATE button. The revision number is displayed as one-second flashes of the NO DOUBLE LED for the integer digit followed by one-second flashes of the DOUBLE LED for the fractional digit. Count the number of flashes on each LED to determine the revision number. Thus one flash of the NO DOUBLE LED followed by two flashes of the DOUBLE LED indicates version 1.2 of the firmware. The sequence repeats one time to aid in discerning the blinks.

Logic Input Electrical Specifications:

RESET and CAL inputs: 30 VDC maximum Upper threshold = +12 volts Lower threshold = +9 volts

Output Relay Specifications:

Maximum switched voltage: 380VAC Maximum switched current: 14 amps N.O., 5 amps N.C, AC resistive, 8 amps DC Maximum switched power: 200W DC, 2,0 VA AC. Minimum required contact load: 12V, 100 mA

"METAL PRESENT" OUTPUT SPECIFICATION:

Output Type: Sourcing ON Voltage (Metal Present): +24 volts DC Max Current: 50 mA Short Circuit Protection: Self-Resetting thermal fuse.

OFF Voltage (No Metal): 0 volts

Troubleshooting:

Should trouble develop, proceed as follows:

1. When power is applied, always have the sensor in air (no metal on the face of the sensor). This allows the controller to normalize the sensor to zero thickness during the startup sequence. If at any time power is interrupted, remove the sensor from metal and then re-apply the power.
2. Check input power to the control module
3. Check the fuse, accessible at the lower left side of the CONTROL MODULE housing.
4. When power is applied, if the green and amber indicators show a response to the metal condition in front of the sensor and the output relay does not switch, check that the RESET input on TB1 has +24VDC applied (if you want the relay to follow the sheet condition). If the unit is to be reset by an external button, check voltage on the RESET terminal when the external button is pressed. The voltage must be greater than +12V when the button is pressed, and less than +9 volts when the button is released.
5. When power is applied, if the DOUBLE indicator is on solidly while the NO DOUBLE indicator is flashing, check for a missing, disconnected, open, or shorted sensor.
6. If both indicators flash alternately, the system is indicating an invalid calibration. The causes can be many. Among them, an attempt to calibrate both double and single on the same thickness material, a shorted sensor, sensor gap too large, incorrect sensor for the material being gauged. To recover from an error condition, after fixing the problem that caused the error, initiate another calibration cycle. If the problem cannot be resolved, call the factory for assistance.
7. If the metal being measured is too close to the upper range of the sensor being used, the range of the sensor can be extended a small amount by using the two-sample feature. To accomplish this, refer to the Calibration section on the two-sample procedure.