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Communications Operation
5.4 Response Time
To let the master PC switch a communications port, it is guarantied that
Powermeter's minimum response time will not be less than 1,75 character time
depending on the baud rate used, and not less than 5 ms. When the RTS option is in
effect, the response will be delayed at 10 ms after the RTS line is asserted high.
The maximum response time depends on the communications protocol applied. In
ASCII mode, the Powermeter's response time will not exceed 80 ms plus 1.75
character time. In Modbus RTU mode, add to this value additional 1.75 character
time.
When using the AX-7 Analog Expander option, the communications link works in
full duplex mode, and is shared between the master PC and AX-7. This means that
master's request received when AX-7 communications is in progress will wait for its
termination. The response time will be increased by the time required for analog
message transmission via communications link plus the link switching time.
The communications link switching time is about 15 ms plus 1.75 character time.
The transmission of the analog output message for one AX-7's channel takes 9
character time, and for all 14 analog channels - 126 character time. In the worst
case, the instrument's response time may be increased by the full AX
-7's message
transmission time, plus double communications link switching time.
5.5 Print Mode
To operate in
Print Mode
, the printer must be fully compatible with the Powermeter
in communications mode and the Powermeter communications parameters should be
set to allow the communications port to interact with the printer. Refer to
Section
5.3
on how to configure the Powermeter communications port.
The instrument sends a fixed format printed report at user
-defined intervals. After
resetting the instrument or completing the current page, the value heading will be
printed on the top of the new page. The printing page height is 60 rows. Each row is
terminated by ASCII characters CR (ASCII 13) and LF (ASCII 10). On each page,
along with a header, 11 readings of electrical values are printed with the date and
time stamps.
