Key coils, Status led coils, Data and coil registers – Maple Systems OIT Family (ASCII) User Manual

Page 16

Key Coils

There are three blocks of discrete OIT coil registers that are used to pass keypress data from the

OIT to the ASCII host: Function Key coils, Screen Dependent Function Key coils (only avail-

able on the OIT5400B), and Numeric Key coils (only available on the OIT5400B). Each uses

consecutive bits (or coils), starting at the address settings specified in the OITware 200 configu-

ration software. The address for the Function Key coils is set in the Configuration Editor. The

addresses for the Screen Dependent Function Key coils and the Numeric Key coils are set in the

Supervisor Editor.

When a function key is pressed, the corresponding Function Key coil or Screen Dependent

Function Key coil is activated. When the coil is cleared depends on how the function key is

configured (for more information, refer to the “Function Keys” section in the Features chap-

ter). When a key that is not a function key is pressed, the corresponding Numeric Key coil is

activated. The coil is cleared when the key is released.

The ASCII host can poll the OIT to determine if a key has been pressed. If the ASCII host re-

quires immediate notification when a function key is pressed, each function key can be pro-

grammed to send an ASCII string to the ASCII host. Refer the the “Sending ASCII Strings

and Displaying Screens” section in the Features chapter.

Status LED Coils

On models equipped with status LEDs (OIT3250/OIT4450/OIT5400), a block of discrete

OIT coil registers is used to control the state of each LED. Each LED represents a single bit

within the register (LED 1=Bit 0, etc.). The Status LED coil address in the OITware 200 con-

figuration software controls which register is displayed on the status LEDs.

These coils, unlike the Function Key coils and Status Bit coils, are optional and do not have

to be used by the OIT programmer. The Status LED coils can be used to continuously moni-

tor OIT coils without having to use the screen display.

Data and Coil Registers

The OIT, when using the ASCII Slave protocol, is capable of storing data internally to be used

as a means of exchanging information between the ASCII host and the OIT operator. The data

is stored in the OIT’s internal memory registers. There are two banks of registers: the data (D)

registers and the coil (C) registers. The data that is stored in the OIT’s data and coil registers is

not retentive, meaning that once power is removed from the OIT the data contents of these reg-

isters is lost. Therefore, it is recommended that the data and coil registers only be used to store

non-critical data. The ASCII host can determine if the OIT has experienced a power reset by

regularly polling the Status Reset coil for a set bit (refer to the “Status Bit Coils” section). The

data and coil registers can be written to or read from by the ASCII host by sending the appropri-

ate control command (refer to the “Control Commands” section).

The OIT’s data and coil registers can be monitored, displayed, and updated by the OIT. This

can be done by configuring the OIT screens to display OIT data and coil registers as embed-

ded data fields (register monitors). When the OIT displays a screen that contains a register

monitor, the OIT reads the specified OIT register address and then displays the data. If the

and optionally sends the new value to the ASCII host (refer to the “Notify Host of

Read/Write Register Monitor Update” section in the Features chapter).

OPERATION

1010-0088, REV02