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Reading Temperatures for Multiple E5ZN Units Section 4-10
4-10 Reading Temperatures for Multiple E5ZN Units
If the present temperature was read from multiple Temperature Controllers
using host communications, there are time differences in the process temper-
atures read from each Temperature Controller, making it difficult to obtain con-
current data.
The PV hold function can be used with the E5ZN to ensure that the data is
concurrent to within 500 ms.
4-10-1 PV Hold
• The PV hold function temporarily stores the present temperature for that
moment as the PV hold value, when the “PV hold” operation command
sent by host communications is received.
• When using multiple E5ZN Units, use host communications to execute
the “PV hold” operation command simultaneously and then read the “PV
hold value” for each E5ZN. This enables highly concurrent temperature
logging.
• PV hold values are overwritten every time the “PV hold” operation com-
mand is executed. Once the PV hold values have been read for the chan-
nel that requires highly simultaneous reading of present temperatures,
execute the next “PV hold” operation command.
• The “PV hold” operation command cannot be executed and the “PV hold
value” cannot be read from the E5ZN-SDL Setting Display Unit.
• When the power is turned OFF, the PV hold values change to 0.
……
Host
computer
Unit No. 0 Unit No. 31
To read present temperatures from all
Temperature Controllers, the PV is read in order
from Unit No. 1 to Unit No. 31. Time passes
between the execution of the first process
(reading from Unit No. 0) until the execution of the
thirty-second process (reading from Unit. No. 31.)
For this reason, there is a time difference
affecting the temperatures obtained from
Units 0 and 31.
Host
computer
(3) “PV hold
value” read.
(1) “PV hold”
executed.
Unit No.
0
Unit No.
15
(2) The present
temperature is held
(1) “PV hold” is executed from the host computer.
(2) The present temperature for each E5ZN Unit
from Units No. 0 to 15 is written simultaneously to
PV hold values.
(3) The PV hold values are read in order, starting
with Unit No. 0.
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