C.4 Error Messages From The Balance - Mettler Toledo AE Série Mode D'emploi

C.4 Error messages from the balance

In certain situations, the balance is not in a condition to carry out the instructions recieved (e.g. an instruction that cannot be
encoded, violation of certain limitations). In such cases, the instruction received is rejected and not carried out. To let the
instruction transmitter know about this, the balance transmits an error message via the data interface.
An error message is composed of two letters:
«ET» Transmission Error
«ES» Syntax Error
«EL» Logistic Error
Transmission errors, «ET»
The «ET» error message is transmitted when the character sequence received from the balance is not correct. Character
sequences are declared not correct when the parity of one or more characters is not correct or the formatting of the individual
characters is not correct (missing stop bit or similiar problems). Such errors occur in operation only very sporadically if the
baud rate and parity settings are correct. Their cause is usually the result of electrical disturbances in the transfer lines;
malfunctions of the electronics are also possible and should be taken into consideration.
Syntax errors, «ES»
Correctly received instructions are declared syntax errors when they do not hold exactly to the instruction form defined in the
preceding chapters. For example, the request instruction «S1R» is acknowledged by the balance with a syntax error because
the correct form is «SIR».
Syntax errors typically occur only in the design phase of the system during test runs. In this phase, the programs of the
controlling computer are developed and tested. In a system that has been tested, program routines should be worked out so
that no syntax errors occur during operation.
Logistic errors, «EL»
Even though the balance has received an instruction that is correct in its transfer and syntax, it still does not mean that it can
be carried out. This would be the case, for example, if more than the permitted 7 characters (plus any decimal points) are
transmitted to the balance display. In such a case, the instruction is ignored and an error message is transferred to the
instruction transmitter.
If the operating speeds of the various balance elements are not regarded, there is a special problem. With instruction
sequences that are too fast, the balance is not capable of working out the sequence. For this reason, it will suppress a number
of instructions and acknowledge them with the error message «EL».
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