DCS Maintenance

Maintenance Philosophy

The maintenance approach is oriented toward module replacement. The use of diagnostics, fault location tables, and troubleshooting guides described in system document, as well as the presence of status lamps (LEDs) on each module, enables isolation of problems to the module level. In addition, any module can be replaced without affecting the operation of any other module, including the module of a fault-tolerant pair.

Preventive Maintenance

The design of DCS equipment and associated peripheral devices is such that scheduled preventive maintenance on the equipment is limited to visual inspections, periodic cleaning procedures, and adjustment of system modules if necessary. While performing these routines, you should check for damaged cables, loose connections, inoperative fans and indicator lamps, wear or binding of drives and fan motors, and take appropriate corrective action.

Enclosures

Perform a general visual inspection and exterior cleaning of each enclosure after the first six months of service. Approximately every 12 months thereafter perform the same, depending on local environmental conditions. Preventive maintenance procedures for enclosures include the following:

  1. Wipe down the exterior of the enclosure with a soft cloth. A damp cloth and/or a nonabrasive cleaner can be used for hard-to-remove spots.
  2. Clean any dust buildup from module heat fins. Use a soft cloth. If heat fins are accessible from rear of enclosure, they can be cleaned during normal operation. Otherwise, modules can be removed and cleaned from front of enclosure during routine equipment shutdowns.
  3. Check fans (if installed) for proper operation.
  4. Check module status indicators for proper operation.
  • Green light indicates normal operation.
  • Red light indicates faulty operation.

Enclosures Air Filters

The vented configurations of all metal enclosures have an air filter located inside the door, behind the vents. Periodically check the condition of the filter for dust/dirt accumulation. Perform the following steps to check the condition of the filter:

  1. Locate the plastic assembly that retains the filter that is on the inside of the door behind the vents.
  2. Unsnap the plastic assembly from the vents and remove the filter.
  3. Wash and replace the filter, or if desired, install a new filter, and snap the filter retainer assembly back onto the vent assembly.

Modular Industrial Workstations

Perform a general visual inspection and exterior cleaning of each workstation as often as necessary to ensure proper operation of the equipment. Preventive maintenance procedures for the workstations should include the following:

  1. Wipe down the exterior of the enclosure with a soft cloth. A damp cloth and/or a nonabrasive cleaner can be used for hard-to-remove spots.
  2. Clean any dust buildup on disk drives (especially the signal connection areas), keyboards, control panels, and monitors. Use a soft cloth.
  3. Check fans (if installed) for proper operation.
  4. Check module status indicators for proper operation.
  • Green light indicates normal operation.
  • Red light indicates faulty operation.

Monitor-Based Peripheral Devices

As a rule, preventive maintenance on these devices should be limited to cleaning only and should be performed as often as necessary, or at least every twelve months.

Wipe down the exterior of the device (excluding the monitor) with a soft cloth. A damp cloth and/or nonabrasive cleaner can be used for hard-to-remove spots.

To clean the monitor, proceed as follows:

  1. Select a screen that does not have direct access to the process, for example, the Initial display.
  2. Remove power from the GCIO unit (annunciators are also deactivated).
  3. Turn the monitor’s power off. Do not move the mouse or depress any keys while the monitor is off. 
  4. Dampen – do not saturate – a clean, lint-free cloth with liquid glass cleaner.
  5. Clean the screen by wiping with damp cloth, using circular wiping motion to avoid streaks.
  6. Carefully dry the screen by wiping with a second clean, lint-free cloth.
  7. Restore power to the monitor and GCIO.

Printers

All printers should be serviced every six months (or after 300 hours of operation), whichever occurs first. Refer to the associated printer user’s guide (packed with the printer) and perform the following:

  1. Perform a general visual inspection and cleaning of the printer.
  2. Remove printer cover and inspect internal moving parts for signs of wear, broken or loose parts, frayed cables, and so on.
  3. Take a clean, dry, soft cloth and dust the area around carriage shaft and platen. Remove any loose particles of paper and dust.
  4. Lubricate printer as described in associated service instructions.
  5. Restore printer power.

Keyboard

A keyboard should be cleaned at a frequency determined by the environment in which it is used.

  1. Use a soft, lint-free cloth dampened with a mild detergent solution to clean the keys and large surfaces. 
  2. Clean confined areas between the keys with a vacuum cleaner equipped with a fine brush attachment.

Mouse

The following care and cleaning procedure applies to both the inner and outer area of the mouse:

  1. The mouse is a very precise mechanical device, so handle it with care. Do not drop, hit, or otherwise subject it to shock.
  2. Do not pull on the cable. It may cause damage to both the cable and connector.
  3. Do not carry the mouse by holding onto the cable.
  4. Be sure to place a clean sheet of paper or use a mouse pad between the mouse and the flat surface. Dirt and grit could collect on the ball. Try not to touch the ball on the bottom.
  5. Do not use the mouse in extreme temperatures or in direct sunlight.
  6. Do not allow the mouse to come in contact with liquid spills (water, solutions, and so forth).
  7. The mouse housing should be cleaned with a lint-free cloth using a mild detergent. Use an unsoiled lint-free cloth to dry housing.
  8. Do not disassemble the mouse. If the ball in the unit needs to be cleaned, remove it from the lower case by detaching the cover to the housing. Do not remove all the screws to remove the ball.
  9. Use a lint-free cloth with mild detergent to clean the ball, and an unsoiled cloth to dry it.

Data Storage Devices

  1. Blow away any lint or dust accumulation on or near the face of the floppy disk and streaming tape drive casings.
  2. Clean the outer plastic surface of the drive with a lint-free cloth or a sponge slightly dampened with water. Wipe off residue and dry with soft, lint-free cloth. Do not use abrasive cleaners, solvents, or strong detergents.
  3. Blow away any lint or dust accumulation on the signal and power connectors at the rear of the drive.
  4. For the streaming tape drive, clean the head using only Freon TF and polyurethane swabs, commonly available with VCR head cleaning kits. Wet the swab with the Freon TF solution, and wipe the head using an up and down motion. Use a dry swab to clean any remaining residue from the head.

Fault Analysis

Through the System Management facility, you can monitor the health of the system and perform diagnostic tests on all the system stations and associated peripheral devices.

Startup Diagnostics

Startup diagnostics are invoked automatically as a result of a power-on reset, an error, or an off-line diagnostic command. The diagnostics exist in each station at all times and are of two basic types:

  • Reportable diagnostic – Tests a station function which, if faulty, does not prevent the error from being reported over the network.
  • Nonreportable diagnostic – Tests a station function which, if faulty, inhibits the station from communicating over the network.

On-line Diagnostics

On-line diagnostics consist of Carrierband LAN LI (LAN Interface) Cable Tests and Nodebus Cable Tests. These tests are either operator-initiated or automatically invoked to isolate faults and to check the integrity of the communication path.

Off-line Diagnostics

Off-line diagnostics are used to check for, or verify the proper “independent” operation of a station’s internal components. These tests do not verify any external reason for failure, thus they can be individually bench tested without regard to the station’s subsystem configuration.

Corrective Maintenance

Module Status Indicators

All power modules, Processor modules, LAN modules, and Fieldbus Modules have red and green status indicators that operate in accordance with the maintenance manual codes.

I/A Series Module Replacement

The maintenance approach is oriented toward module replacement. Fault analysis provides assistance with isolating station and peripheral faults. The presence of status lamps (LEDs) on each module enables an initial detection of problems that can exist on the module level. In addition, any module can be replaced without affecting the operation of any other module, including the other module of a fault-tolerant pair.

Replacement of modules is similar to installation, which is described in the System Equipment Installation.