User Manual

How to use the Checksum feature
F-
2 ADAM 4000 Series User’s Manual
A c hecksum helps you detect comm unication errors between the host
and m odule. This feat ure a dds t wo ext ra checksum characters to t he
command or response string; therefore, it reduces the throughput.
F.1 Checksum Enable/Disable
In order t o e nable co nfiguration o f a m odule’s c hecksum feature, its
INIT* term inal sh ould be sh orted to its GND term inal. Th en, th e
module should be rebooted. The checksum feature is enabled by setting
bit 6 of t he data fo rmat/checksum param eter t o 1. On the ot her hand,
the checksum i s disabled by setting the parameter t o 0. Whenever t he
checksum feature is used, all the co nnected devices i ncluding the host
computer should be in enable mode.
The c hecksum is re presented by a 2-c haracter ASCII hexadecimal
format and is transmitted just prior to the carriage return. The checksum
equals to t he result af ter performing m odulus-256 (100h) of all th e
ASCII values’ sum preceding the checksum. If the checksum is missing
or incorrect, the module will not respond.
Example 1
The following exam ple is an Anal og Data In c ommand and response
when the checksum is enabled:
Command: #0588(CR)
Response: +3 .56719D(CR)
The input value of the module at addr ess 05h is +3 .5671 V. (The data
format i s i n e ngineering units.) The c ommand c hecksum ( 88h) i s t he
sum of the ASCII values for the following characters: #, 0, and 5. The
response c hecksum ( 9Dh) i s t he s um of t he A SCII values for t he
following characters: “>”, “+”, “3”, “.”, “5”, “6”, “7”, and “1”.