Boundless ADDS 6700 Manual download pdf (Page 135)

-DIN,

-DIN &

- DIN Controllers & Indicators - Product Manual

Page 130 ASCII Communications 59305, Issue 7 – March 2014

Type 4 Message

L {N} {P} I * or R {N} {P} I *

This type of message is sent by the master device to the addressed slave device, following a

successful Type 3 transaction with the same slave device. Provided that the {DATA} content

and the parameter specified in the preceding Type 3 message are still valid, the slave device

will then set the parameter to the desired value and will reply in the form:

L {N} {P} {DATA} A *

where {DATA} is the new value of the parameter. If the new value or parameter specified is

invalid, the slave device will reply with a negative acknowledgement in the form:

L {N} {P} {DATA} N *

where {DATA} is indeterminate. If the immediately preceding message received by the slave

device was not a Type 3 message, the Type 4 message is ignored.

Error Response

The circumstances under which a message received from the master device is ignored are:

Parity error detected

Syntax error detected

Timeout elapsed

Receipt of a Type 4 message without a preceding Type 3 command message.

Negative acknowledgements will be returned if, in spite of the received message being

notionally correct, the slave device cannot supply the requested information or perform the

requested operation. The {DATA} element of a negative acknowledgement will be

indeterminate.

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Boundless ADDS 6700 Manual Page 135