Cautions On Connection With External System - Hitachi 902 Service Manual

16.10 Cautions on Connection with External System

(1) For connection with this protocol, adopt the point-to-point system.
(2) Although the end-of-data code is changeable on the system setting screen, the host must
send the same end-of-data code as on the analyzer side. If the code does not match
between them, alarm is issued.
(3) EXT is always added to the end-of-data code in each text. Whenever data beyond 256
bytes is transferred, therefore, the analyzer adds not ETB but ETX.
For the host, a frame character ':' is the final message when the data for one sample is
sent in more than one text. So pay attention when taking in the data.
(4) As a rule, the analyzer sends the ANY frame to the host in response to a request from it in
the following cases.
(a) On request for analytical data transfer from the host, the relevant sample is not
stored on the FD.
(b) Analytical data cannot be read from the FD due to occurrence of an error in it during
batch transfer of analytical data.
(5) The communication controller in the analyzer is initialized in the following cases.
(a) Power supply is turned on.
(b) [RUN] (highlighted) is specified for host communication parameter (any of baud rate,
parity data bit, stop bit, end-of-data code and text length is changed through the
screen). At this time, the first event request (RES, SPE) from the host is ignored.
After changing a communication parameter, attention should be paid to event.
(6) If an error is detected on a text transferred from the host, the analyzer sends REP
(resending request) until the normal text is received.
(7) Secure at least 100 msec before transfer from the host to analyzer.
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