Trouble Shooting - KEP MMI-7 Series Installation Instruction

7.2 BATTERY REPLACEMENT
The MMI-7xx takes one coin type of CR2032 lithium battery to backup the recipe data and keep the RTC
running.
Battery specification: CR2032 3V lithium battery.
Steps for battery replacement:
1. Use EasyManager to backup the retentive memory data.
2. Turn off the screen and open its rear cover.
3. Use a small screwdriver to remove the battery from the socket.
4. Insert a new battery into the socket.
5. Put on the rear cover.
6. Reset the RTC time and download the retentive memory data.

8.0 Trouble Shooting

8.1 POWER PROBLEMS
Problems on power up: Unit does not light or unit lights but does not display any windows.
1. Check wiring for proper polarity.
2. Check power Supply for proper Voltage and Current capacity.
3. Check fuse.
Problems during operation: Faulty unit operation may be due to problems with power quality. The
MMI has been designed to work in environments where electrical noise is present. However, extreme
electrical noise still causes problems. Make sure that the system is properly earth grounded.
8.2 COMMUNICATIONS PROBLEMS
Sometimes communications fail. When communications fail, the unit automatically tries to establish the
communications link again. During the time the unit is establishing communications, the touchscreen of
the unit does not respond. Function key operations are interrupted. The implication is that the unit should
not be used for Emergency Stop applications. A loss of communications can happen at any time. Using
the function keys on the unit for critical operations can lead to a potential disaster. It is good programming
practice to allow for safe operation in case of interface failure.
There are various reasons why this happens;
Improper programming: If the MMI window is programmed to access data from an invalid register or
bit address for the PLC, the unit receives an error message from the PLC. The unit interprets this as a loss
in communications. Be sure that all data points being displayed are valid for the PLC that is connected.
Loose or incorrect cables: Make sure that all cables are secured and configured properly for the PLC.
Time outs: Make sure that the PLC is responding to requests from the MMI in a timely manner.
Power loss: Make sure the PLC has power and is running properly.
Electrical noise: Faulty unit operation may be due to problems with power quality. The MMI has been
designed to work in environments where electrical noise is present. However, extreme electrical noise still
causes problems. Make sure that the system is properly earth grounded.
The use of proper grounding techniques insures reliable communications. Make sure the controller and
the MMI are connected to good earth ground sites. This allows EMI (Electro-Magnetic Interference,
commonly called electrical noise) to be channeled to ground where it can no longer disrupt electrical
operations. Be sure to route communications cables in separate bundles and locations from AC power and
control wiring. Do not run communications cables near solenoid and relay coils or AC and DC drive
controllers. Care should also be taken to locate the MMI itself away from sources of EMI.
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