Calculating the checksum – Rockwell Automation 2098-DSD-xxx Ultra3000 Host Commands for Serial Interface User Manual

Page 167

Advertising
background image

Publication 2098-RM003A-EN-P October 2001

Using Host Commands

C-3

6. Select the Settings tab

A. Verify that Emulation is set to VT100.

B. Click on the ASCII Setup button and make these selections:

Calculating the Checksum

The checksum value is used to verify that the data transferred
correctly. When the Ultra family drive receives a command, it verifies
that the checksum is correct before acting on the data.

To calculate the checksum value, you must obtain the ASCII value of
each character in the command string. (A decimal to ASCII conversion
table is on page C-8.) For example, the ASCII value for the number 5
is 53. To calculate the checksum value, you must add together all of
the ASCII values for the numbers or letters in the command you want
to send, subtract this value from 256, convert the result to a
hexadecimal number, and then use only the last two digits. It may
seem complicated, but after an exercise or two it will become clear.

Selected (checkmark)

Not Selected (no checkmark)

Echo typed characters locally

Send line ends with line feeds

Append line feeds to incoming line
ends

Force incoming data to 7 bit ASCII

Wrap lines that exceed terminal width

Advertising