LINK Systems OmniLink - PLC Interface - Manual (Page 27)

June 5, 2000 Man ual Rev 1 .0
4.2
NOTE: What the PLC does when a parameter is changed or an action key is pressed is
completely dependent on the PLC program.
“Last Fault” line (“d”). To clear the top stop, the stop condition must be corrected
(communications restored etc.) and the “RESET ERROR” softkey must be pressed. Note
that this key will only appear when an error condition has been detected.
Item “c” The current communications status is displayed here. Note that this is entirely different
from a PLC screen or parameter status message. This line shows the state of
communications between the OmniLink OIT and the PLC. If the OmniLink tries to send
information to the PLC and no response or an incorrect response is received, the
OmniLink will try 2 more times before reporting an error. After the error is reported, the
OmniLink will continue to try to reestablish communications. If communications are
restored, the status will go back to “OK”. Note however, that even a momentary loss of
communication will result in a top stop and the error will be shown on the “Last Fault”
line to allow diagnosis of the problem.
Item “d” The “Last Fault” line shows the reason, if any, that the PLC Interface signaled the press
to top stop. Under normal conditions, this should say “None”. When a fault is latched
here, the “RESET ERROR” softkey will appear. Press the “RESET ERROR” key to
attempt to clear the fault.
Item “e” This is the PLC Screen Status message area. The status labels (“System Status” and
“Hyd. Pump Stat.” in this example) are the ones configured in Figure 3.7. The messages
shown are selected by the PLC using the communications protocol discussed in section 5.
Note that this area may not be present as the PLC Interface does not require PLC status
messages to be used.
Item “f” This is the screen name configured in the screen of Figure 3.2. This is quite useful when
more than one PLC screen is being used. In this example, it tells the operator that he is
working with the die clamp system.
Item “g” These softkeys are the PLC action softkeys as configured in the screen of Figure 3.6.
Depending on configuration, there will be 0 to 5 softkeys present.
The main part of the screen displays the user defined parameters that were set up in the screen of Figure
3.5. In the example above, there are 4 “Status Only” parameters that indicate the state of 4 individual die
clamps. In addition, there is a “Numeric Only” parameter that sets the die clamp hydraulic pressure. To
change a numeric parameter, place the editing cursor on the desired parameter and enter a new number.
If the new number is less than the minimum value configured for that parameter or is greater than the
maximum value configured for that parameter, a message will appear explaining the condition.
Otherwise, if the number is accepted, it will be sent to the PLC. Note that access to this screen must be
gained by the RUN/PROG keyswitch or an access code depending on the system configuration as
explained in section 2. If access codes are used, each PLC screen can be separately controlled. For
instance, a die clamp screen and a rolling bolster screen can be configured. A user could be set up to
have access to the die clamp parameters but not the rolling bolster parameters.