Ascii strings – Maple Systems OIT Family (ASCII) User Manual

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ASCII Strings

Sent from the OIT

ASCII strings are sent from the OIT to the ASCII host for three reasons:

•

in response to a control command sent from the ASCII host (refer to the “Control

Commands” section)

•

whenever a function key is pressed that has predefined ASCII strings (refer to the

“Sending ASCII Strings and Displaying Screens" section in the Features chapter)

•

whenever one of the OIT’s internal data or coil registers are changed when the “Notify

Host of Read/Write Register Monitor Updates” feature is enabled (refer to the “Notify

Host of Read/Write Register Monitor Updates” section in the Features chapter).

Sent from the ASCII Host

Control commands (for a definition of the control commands, refer to the “Control Commands”

section) are the only type of communication allowed from the ASCII host to the OIT.

A common question is “How do I display a string of characters on the OIT?”. There are two

ways to accomplish this depending on whether the strings can be predefined.

If you know what the strings will be when programming the OIT, the strings can be prepro-

grammed into the OIT’s 500 screens. Then when the ASCII host sends the Display Screen

control command with the appropriate message number, the OIT will display that message.

A string of characters may also be “embedded” into each OIT screen by using the ASCII Char

registers being monitored using the Write String control command. This powerful feature en-

ables the ASCII host to change text strings that are displayed on any screen of the OIT.

Each ASCII Char register monitor displays the two ASCII printable characters stored in a data

(with consecutive OIT data register addresses) embedded next to each other on the OIT screen.

For example, suppose that you wish to display the following screen on the OIT with the

ability to change the type of fruit:

Please choose type of fruit: Bananas

Press F1 key for choices. Qty? 15

Create a series of four ASCII Char register monitors. When programming the screen using

the OITware 200 configuration software, the screen would look like the following:

Please choose type of fruit: AAAAAAAA

Press F1 key for choices. Qty? ##

Each AA represents one ASCII Char register monitor configured to monitor a consecu-

tive OIT data register (for example, D10, D11, D12, and D13). The ASCII host can

change the characters displayed in these register monitors by sending the Write String

control command. To change the fruit selection to peaches, the ASCII host would send:

ESC

S 0010 PEACHES

STX

This places the characters “PE” in D10, “AC” in D11, “HE” in D12, and “S ” in D13.

With the Write String control command, the ASCII host can write up to 40 characters at once!

OPERATION

1010-0088, REV02