Maple Systems OIT Family (ASCII) - Manual (Page 27)

Like message screens, recipe screens are capable of:
• displaying text and characters from the extended character set
• displaying up to 25 register monitors
• sending the screen contents to a printer for hard copy
• displaying one line of horizontal scrolling text up to 128 characters long
• displaying blinking characters
• displaying for a preset length of time from 1 to 255 seconds
• beeping on display for two seconds
• help screens are available.
Unlike message screens, recipe screens are incapable of:
• chaining to message screens
• displaying the current time and/or date from the OIT’s real time clock.
Each recipe can include up to 25 register monitors. The OIT operator can change the values
in the read/write register monitors prior to starting the process, which facilitates changes to
the recipe such as quantity or size of run.
After the recipe screen has been configured, it operates in the following manner:
• When a recipe screen is initially displayed on the screen, the initiator is set to ‘N’ and the
gate coil is set to normally off (normally off can mean either a set or cleared coil depending
upon how the gate coil was programmed).
• The OIT operator uses the arrow keys to navigate the screen and alter the read/write
register monitors prior to starting the process. If the “Notify Host of Read/Write Register
Monitor Updates” feature is enabled, each time a value in a read/write register monitor is
changed the OIT will send the new value to the ASCII host. If this feature is disabled, the
ASCII host will have to read the values in the OIT’s data registers using the Read OIT
Memory control command.
• When the OIT operator is ready to start the process, the OIT operator changes the initiator
from ‘N’ to ‘Y’ by pressing the Toggle key and then pressing the Enter key.
• When the Enter key is pressed, the OIT automatically writes the preset constant values to
the predefined OIT data registers and sets the gate coil to normally on. If the “Notify Host
of Read/Write Register Monitor Updates” feature is enabled, the OIT notifies the ASCII
host that the gate coil was activated and sends the preset constant values. If this feature is
disabled, the ASCII host will have to read the values in the OIT’s data and coil registers,
using the Read OIT Memory control command, to find out the preset constant values and
the state of the gate coil. By turning the gate coil on, the OIT signals to the ASCII host that
it may now start the batch processing.
Alarm Screens
Alarm screens are used to signal the OIT operator on the plant floor that an emergency condi-
tion has occurred. Because of the importance of alarm screens, they have three special prop-
erties which no other type of screen has:
1. An alarm screen displayed on the OIT cannot be removed from the display until the
OIT operator presses the Alarm Ack key or the ASCII host cancels the alarm. This
guarantees that the alarm will be seen by the OIT operator.
26 OIT Family Operation Manual (ASCII)
1010-0088, REV02