Maple Systems OIT Family (ASCII) - Manual (Page 20)

Performance Considerations
OIT Memory Requirements
Maple Systems’ OIT Family products have FLASH memory for storing program code, pro-
tocol code, and system configuration information. These devices are of the latest technology
and permit easy firmware upgrades, protocol enhancements, and safe storage of important
configuration data. Each OIT is capable of storing a maximum of 500 screens.
Data is stored dynamically to get the most out of the memory space allocated for configura-
tion data. Memory is used only as necessary instead of allocating a certain number of bytes
per message in the OIT. This means that the maximum number of screens which can actually
be created is determined by how many characters the system programmer places into each
screen, how many register monitors are on each screen, and how many special attributes are
used (for example, blinking characters, scroll lines, etc.). The OITware 200 configuration
software keeps the system programmer informed of the remaining memory at all times.
Using this storage technique, it is very difficult to actually use all of the available memory in
a single application.
System Speed
The OIT hardware and multitasking software are designed in such a way that system perfor-
mance is only limited by the communications speed and baud rate of the ASCII host.
Response Time of OIT to Control Commands
The speed of response to an ASCII host’s control command varies and is dependent upon a number
of factors. Under normal conditions, the OIT responds within a few milliseconds to the control
command request. However, the following conditions should also be taken into consideration
when trying to determine how long the host should wait for a response from the OIT:
• If no register monitors are currently displayed on the OIT screen, the OIT checks the ASCII
host for a control command every 200 milliseconds. If a register monitor is currently
displayed on the OIT screen, the OIT checks the ASCII host for a control command
continuously. We recommend that the ASCII host wait for at least 250 milliseconds before
concluding that an OIT timeout has occurred.
• If the OIT is configured with a Turnaround delay, then this delay must be added to any
other delays that may occur, since the OIT waits for the programmed Turnaround delay
time before sending back a response.
• If the OIT is configured with an Intercharacter delay, then this delay must also be added to
any other delays that may occur, since the OIT waits for the programmed Intercharacter
delay time before concluding that a control command error has occurred. The OIT then
responds with an error code.
Programming the OIT
The OIT must be configured for a particular protocol before use. The OITware 200 configu-
ration software is used to program the OIT for connection to an ASCII host. A configuration
file must be downloaded to the OIT before the OIT can be used. For detailed instructions on
installing the OITware 200 configuration software and configuring your OIT with the
OITware 200 configuration software, please refer to the OITware 200 User’s Guide.
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