Specifications

Command Set 4-20
ERROR MESSAGES
The D1000 modules feature extensive error checking on input commands
to avoid erroneous operation. Any errors detected will result in an error
message and the command will be aborted.
All error messages begin with “?”, followed by the channel address, a space
and error description. The error messages have the same format for either
the ‘ $ ‘ or ‘ # ‘ prompts. For example:
?1 SYNTAX ERROR
There are eight error messages, and each error message begins with a
different character. It is easy for a computer program to identify the error
without having to read the entire string.
ADDRESS ERROR
There are six ASCII values that are illegal for use as a module address:
NULL ($00), CR ($0D), $ ($24), # ($23), { ($7B) and } ($7D). The ADDRESS
ERROR will occur when an attempt is made to load an illegal address into
a module with the SetUp (SU) command. An attempt to load an address
greater than $7F will produce an error.
BAD CHECKSUM
This error is caused by an incorrect checksum included in the command
string. The module recognizes any two hex characters appended to a
command string as a checksum. Usually a BAD CHECKSUM error is due to
noise or interference on the communications line. Often, repeating the
command solves the problem. If the error persists, either the checksum is
calculated incorrectly or there is a problem with the communications
channel. More reliable transmissions might be obtained by using a lower
baud rate.
COMMAND ERROR
This error occurs when the two-character command is not recognized by the
module. Often this error results when the command is sent with lower-case
letters. All valid commands are upper-case.
NOT READY
If a module is reset, it performs a self-calibration routine which takes 2-3
seconds to complete. Any commands sent to the module during the self-
calibration period will result in a NOT READY error. When this occurs, simply
wait a couple seconds and repeat the command.
The module may be reset in three ways: a power-up reset, a Remote Reset
(RR) command, or an internal reset. All modules contain a ‘watchdog’ timer