Specifications

Interface Specifics 51

that SMARTSET reflects the changes you made manually in ASCII Setup. When

writing a driver, the SMARTSET utility is valuable for understanding the

query/response/set interaction for the various commands and for verifying the

settings you program into the controller.

You may wish to experiment with other queries in ASCII Setup. Type "o" to query

the Owner string. Type "g" to download the whole configuration of the controller.

You should be able to identify each packet and their contents by referring to

Chapter 6.

From the Main Menu, type "R" and select Soft Reset to restore the default settings

of the controller. Exit SMARTSET.

In the next section, we will detail the communication at an even lower level the

specifics for each type of interface: serial, PC-Bus, and Micro Channel. The

SMARTSET utility hides these details, just as you may hide them at a certain level

when developing a driver that supports multiple interfaces.

INTERFACE SPECIFICS

Serial Controllers

The serial interface uses the eight-byte packet with an additional Lead-in byte and

a trailing Checksum byte for a total of ten bytes.

An optional Key byte may also be included. See page 52 for more information.

Lead-in Byte

The Lead-in byte is used to signal the start of a packet. The standard Lead-in byte

is an ASCII 'U' (55h). This character was chosen due to its distinctive alternating

bit pattern.

The Lead-in byte is different if the optional Key byte is included in the packet. See

Key Byte, page 52, for more information.

Checksum Byte

The trailing Checksum byte may be used to validate the serial communication and

to synchronize with the received data stream.

The Checksum is calculated as follows: