Case Studies
Standard Aero Flies High ...
thanks to automated time card system
Laura Briedis, Contributing Editor - ID News
Standard Aero's success can be linked in part to its data capture and control
unit that has set an industry standard in successful bar coding
applications.
Last year, Canada's largest independent aircraft engine and accessory repair
and overhaul facility overhauled its manual time and attendance system to
feature bar coding. At the company's main facility in Winnipeg, Canada, each of
the 700 employees--from the president down to the shop workers--was issued an ID
card with a Code 39 bar code printed on the front that operators use to log time
spent on jobs. On the back of the card is a magnetic stripe for security-
controlled door access.
Seventy LINX data terminals located throughout the 270,000-suare-foot
facility perform point-of-origin bar code and magnetic stripe data collection.
The LINX accepts data from bar codes, magnetic stripe cards, bar code wands,
lasers and built-in keyboards.
Before the company installed the LINX terminals, the employees filled out a
manual time sheet, accounting for shift time, then handed the time sheet to the
office where a labor entry clerk entered the data into a Hewlett-Packard 3000
mainframe computer.
"This was yesterday's time they were entering, so our records were a day
behind," says George Goold, director of MIS for Standard Aero.
The Auto ID system not only improved the time response but the data accuracy.
"The accuracy now with bar code shop orders is close to 99%," Goold says. "Every
time an operator logs on, he is forcing the system to be up to date.
"The biggest benefit is that we can now do proper, competitive analysis of
time going against jobs. Our quotes now are more competitive because we know the
actual cost of doing a job."
APPLICATION-ORIENTED DATA COLLECTION
"When the company wanted to upgrade from a manual system to a complete bar
coding system, the LINX terminal was ideal for its needs," says Vince Panacci,
product manager for OCR Ltd., who consulted on the project.
"What sold this system is that it is a direct link to a Hewlett-Packard
3000," Panacci says. "In other words, the company is using its existing
mainframe software and using the LINX to upload the data collection portion from
the shop floor.
"Because the terminals are intelligent, you can program them for different
transactions. We try to offload as much as possible from the mainframe to the
LINX terminal. All the prompting and field validation can be done through
terminals."
"Secondly, with real time the company can get a response on the floor at the
moment needed," says OCR Ltd. Software Manager Jack Art. "The information would
not have to go through night batch code testing, but rather directly off the
database so the information they receive would be timely and accurate."
"The third selling point," says Panacci, "was redundancy in the system which
features a fault-tolerant network and memory that senses that the host is down
and to collect the data and upload it once the host is back up."
FAULT TOLERANCE NEEDED
Because Standard Aero has a 24-hour shop, fault-tolerant configurations are
essential. In addition the company is located in Western Canada, where prairie
storms often occur, which can cause power failures. As a result, the company
needed to ensure the data would not get lost and would be retained in the
network.
"When the power goes down, it will retain the information in the unit because
it has a lithium battery back-up," Art says. "When the power comes back up, even
though the mainframe might not come up immediately, the station will operate in
an offline mode so workers can still use it. Then when the mainframe comes back
up, the information that has been collected and stored in the station then would
be sent up to the mainframe."
At the time that an operator processes any transaction, the computers verify
that the sequence is logging onto is the current sequence on the system before
accepting that transaction. "If it is not, we don't allow him to log on," says
Ed Ferbers, and industrial engineer for Standard Aero. "So there is two-way
feedback. The operators not only are giving information to the system, but they
are being told what the current sequence is, etc."
As each sequence is completed, the next operator logs onto the sequence and
the operator's ID number, time of transaction and type of transaction are
recoded and sent to the mainframe, which either accepts it or rejects it. When
the operator finishes a job, he only needs to log onto the next job shop order
and indicate whether the previous job sequence was completed.
"This way we can know at any given time exactly where a unit is as far as
stage of completion in order to physically find that unit and in order to bill
as quickly as possible," Goold says. "Now we have a much more accurate picture
of what our actual times are because employees are forced to process a
transaction at the time they change jobs."
MENU-DRIVEN CONFIGURATIONS
The terminal conforms to a particular application environment through a
series of menus. At Standard Aero, LINX's BARCON programming language runs in
each reader, but the company developed 25 tailored bar code menus as well for
specific job tasks to make the system easier for the shop floor user.
For example, in a small area where workers receive a part and do one or two
operations on it, only those three functions are included on a menu. In reworks,
the menus keep track of machine usage, so the company can do capacity planning
on the equipment.
"We have different menus in particular areas, but the same program runs on
both readers, " Goold says. "Even though we have 70 readers, everything works
through one port on the HP3000."
DATA FLOW IN THE NETWORK
This is how the network works:
- The LINX program creates a record. Data records originate
at individual LINX stations under the control of the BARCON
program running the station. The programmer can create a data
record of up to 80 bytes. This can include data scanned from a bar
code or entered from a keypad.
- The program stores the record.The program stores the
record in battery-backed-op RAM, where it awaits transmission to
the host computer system. It can hold a record for more than four
years--even without power.
- The host computer polls the master station. Polling can be
accomplished with a variety of off-the-shelf asynchronous drivers
and programs are available for this task.
- The master station polls another terminal. Sub-masters poll
their assigned terminals and respond to polls for the master on
behalf of those terminals.
- The terminal creates a data packet. When a station is
polled and it has data records to send, it responds by creating a
data packet.
- The data packet is transmitted to the master. The packet
will be created in response to a sub-master poll and it will be
transmitted to the master via the sub-master.
- The master station acknowledges or requests
retransmission. The master examines the packet's Cyclic
Redundancy Checking (CRC) and either informs the terminal that the
packet was successfully received or requests retransmission due to
a detected error.
- The station discards the acknowledged record. After the
master has acknowledged successful receipt of the data packet, the
terminal purges the associated data record from its
battery-backed-up RAM.
- Master sends the data to the host with a 10 byte header. A
header that identifies the originating station's ID, the program
transaction number, the packet retry count and the network
sequence number is sent. This is followed by the original data
record, extracted from the packet.
THE ALTERNATE MASTER
One of the biggest advantages of the network is its fault-tolerant
configurations, which ensure that no data is lost on the network since every
terminal holds its collected data until acceptance by the host computer is
verified.
In addition to collecting data, the terminal can function as an alternate
master. This is established using the terminal keypad during the terminal
installation and setup phase. Although this station will have a direct path to
the host system, it will not directly talk to the host as long as the master
station maintains the network activity.
The alternate master monitors the polling actions of the master. If the
master does not poll the networked terminals within 90 seconds, the alternate
master will inform the master terminal and all other terminals in the network
that it is assuming control of the network. Within less than 120 seconds after
determining the master was inactive, the alternate master will issue new Ids to
every member of the network, causing them to recognize that the alternate is in
charge and transferring data to the host system.
Once the failed master resumes operation, it will automatically resume its
network control task and the alternate master will return to its original
monitoring role.
THE ALTERNATE SUB-MASTER
The network activities of a sub-maser are identical to a master, except that
it controls a tributary and connects to the backbone through another terminal
which has network responsibilities as a concentrator.
The concentrator is always polling a connected sub-master. If the sub-master
has a data record of its won, or that of one of its tributary units to send to
the host system, it creates a data packet and forwards it to the master through
the concentrator. If the host system issues a directive or makes a request of a
specific sub-master, the master will issue its polls to the sub-master via the
concentrator. No operator action is required.
Host-system or master communication with the tributary terminals occurs
through the alternate sub-master until the original sub-master either recovers
and comes back on line, or is replaced by a spare unit and given the sub-
master's original ID. If this is done, the alternate sub-master will
automatically relinquish control in the same manner as the alternate master.
FUTURE APPLICATIONS
Once Standard Aero personnel master this system, it will address not only
today's needs, but tomorrow's.
"In the future, we are looking at electronic inspection, in which our quality
inspectors use an electronic ID card instead of stamping the shop orders for
approval," Goold says. "We are also looking at inventory control and
electronically bar coding batch numbers."
With current and future applications, time accounting, job costing, labor
scheduling, machine monitoring, access control and quality control will be
"linxed" to the company's existing network to do it all.
