Technical_reference - 第124页
Technical Service Manual 124 Revision Dat e: August 2004 SMEMA INTERFACE The SMEMA Inter face is : ! Standard, (installed on all ovens ) ) An option, (NOT installed on all ovens ) DESCRIPTION (SMEMA is the acr ony m for …
Technical Service Manual 123 Revision Date: August 2004
After the ‘rail out’ function has been tested, the ‘rail in’ function check out should be greatly reduced. Activate the ‘rail in’
function in the Oven Operation Program (this is assuming you have already logged into the software as previously
described). The parts of the auto rail circuit which can be a problem, is the ‘direction relay’ K8 and the ‘rail in’ limit switch.
The test procedure for these components would be the same as described for the ‘rail out’ circuit.
The final check out procedure is to verify that the linear transducer feedback signal is being received and processed by
the computer.
(If the linear transducer is operating and connected properly, the loop feedback value should be 2 – 10 VDC)
Run the “Manual rail adjust” within the Oven Operation Program. NOTE: This operation may require a password.
When the rail is moving inward, the value should decrease. If the transducer loop feedback value is not within the
prescribed range, check the wiring from the transducer to the controller. The transducer signal output is 0 to +10 VDC.
The signal level from the transducer is then reduced to a 60 mV level by a voltage divider circuit. A possible error with
this circuit is incorrect resistor values used on the voltage divider circuit. Verify the polarity of the transducer signal output
to be correct.
Technical Service Manual 124 Revision Date: August 2004
SMEMA INTERFACE
The SMEMA Interface is:
! Standard, (installed on all ovens) ) An option, (NOT installed on all ovens)
DESCRIPTION
(SMEMA is the acronym for Surface Mount Equipment Manufacturer’s Association)
The SMEMA electrical interface option for the Reflow Oven is intended to comply with the SMEMA Electrical Interface
Standard 1.2. It provides signals from the Reflow Oven to the upline/downline equipment in the process line.
A PLC is mounted inside the electrical enclosure; a photo-sensor is mounted on brackets above each end of the
conveyor(s). A 14 pin round connector is mounted on each end of the Reflow Oven. The SMEMA interface receives
power from the Reflow Oven to operate. (The PLC operates two SMEMA circuits.) The SMEMA interface accepts a
'Board Available' signal from the upline (onload side) of the Reflow Oven on pins 3&4 of the onload connector. It replies
with a 'Busy' signal on pins 1&2 of the onload connector to the machine upline. On the downline (offload) side, a 'Board
Available' signal is sent on pins 3&4 and looks for a 'Busy' signal to come back on pins 1&2 of the offload connector.
Because the Reflow Oven should not be stopped with product in the heat zone, the busy signal coming from the downline
end is used to generate the busy signal for the upline equipment without stopping the Reflow Oven. When all of the
conditions are ‘False’, the Reflow Oven is “not busy” and will accept more product from the upline equipment. If any of
the conditions are ‘True’, the Reflow Oven will transmit a "busy" signal to the upline equipment. This should stop the
upline equipment from sending product to the Reflow Oven, thus preventing a product buildup.
The upline “busy” signal can be a result of one (or more) of the following:
1. Board at ‘on-load’
2. Board Jam at off-load
3. Downline machine has not sent ‘ready’ signal for 2 boards
4. Oven is NOT ‘Process Ready’
5. The (settable) spacing between boards has not been satisfied.
The busy signal from the Reflow Oven to the upline piece of equipment is designed to provide a space equal to
approximately 1/2 the product length between each product under normal operation. The board available signal sent from
the upline equipment is not implemented because the oven should not be stopped and started. The board available signal
sent from the Reflow Oven to downline equipment is a notification of product coming out of the oven.
When a board's leading edge passes under the onload sensor it triggers the busy signal to be true (on) for 1.5 board
lengths. This tells the upline equipment feeding the Reflow Oven to wait for 1.5 board lengths before feeding another
piece to the Reflow Oven. When the board exits the oven and the leading edge passes under the offload sensor, it
triggers the board available signal to go true (on) 1 second later and to stay true for one board length. This signals the
downline equipment receiving product from the Reflow Oven to expect a board at that time. The 1-second delay is to
ignore false signals created when the photocell senses the conveyor belt.
The PLC controls the delays and triggers the operation of the interface off of the process ready signal. If the machine is
NOT process ready, the SMEMA interface will signal busy to the upline equipment.
Technical Service Manual 125 Revision Date: August 2004
SETUP
The SMEMA interface requires that the connections be made between adjoining machines and the Reflow Oven, using
the SMEMA connectors at the onload and offload ends. The PLC is pre-programmed and the sensors are preset at the
factory. The SMEMA interface is installed and fully tested at the factory before shipping. The user should not need to
adjust the SMEMA interface after initial connections have been made.
OPERATION
Action by the Reflow Oven operator is not necessary for the SMEMA interface to function. As long as the upline /
downline connections are made and a component failure has not occurred, operation will be automatic when the Reflow
Oven is powered up.
NOTE
Ovens with a Dual Rail conveyor (with two sets of rails and chains) have two separate sets SMEMA Interface sensors
making separate input(s) to the PLC.
Each conveyor must be ready to receive product before it independently sends a “Ready” signal to its respective “upline”
equipment.
Either conveyor can send a “Product at Offload” signal to the “downline” equipment.