Yokogawa Data Acquisition with PID Control CX2000 - Manual (Page 21)

1-9
IM 04L31A01-01E
Explanation of Functions
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2
1
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10
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12
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Data that can be used in the analog retransmission equation are as follows:
• Measured input data, measured computation data, internal/external control data, and
communication input data.
• Constants (constants used in measurement computations can not be used)
• Control input data
• Control output module, expansion module DIO, and remote input for measurement
• Internal switches
Computation Error
You can specify the output method when a computation error occurs, such as when an
overrange occurs on the computed results of analog retransmission.
Over: 105% of span
Under: –5% of span
Display/Recording of Analog Retransmission
The output value of analog retransmission is displayed/recorded as the OUT value of the
loop specified for analog retransmission. PV and SP are not displayed or recorded.
Internal Switches (Style Number S3 or Later)
Internal switches are software switches that are not output externally, and are used only
for internal processing. The switches have the following uses.
• The same output destination as the output relay
Control alarm, measurement alarm, measurement computation alarm, time event, PV
event, program pattern end signal, logic computation output.
• DIO operation monitoring function
• Use of computation data in the PV/SP computation and the analog retransmission
equation
• Assignment of actions to changes in the status of the internal switches
• Reads the operation ON/OFF and internal switch statuses using the communication
function.
The status of the internal switches is “nonhold.”
DIO Operation Monitoring Function (Style Number S3 or Later)
Internal Switches and DIO Operation Monitoring Function
Since the internal switches are used exclusively for internal processing, the status of the
switches cannot be confirmed externally. With the DIO operation monitoring function,
you can output the status of the internal switches by assigning a DO to the internal
switch. You can output the ON and OFF statuses of the internal switches to separate
DOs. Also, you can switch between Auto and Manual operation modes. When in Auto
mode, the status of the internal switches is output. When in Manual mode, you can
manually switch between DO ON(1) and OFF (0). Internal switch output has priority over
alarm output and event output. If the same DO is assigned to an internal switch and an
alarm output, alarms cannot be output.
Internal switch SW01
AUTO MAN
DO001
Internal switch SW02
DO003
AUTO MAN
DO004
ON OFF
When DO01 is assigned to SW01 When DO003 is assigned to the
ON signal of SW02, and DO004
is assigned to the OFF signal
In the above cases, even if D001, DO003, and DO004 are specified for alarm output, the
alarm signal is not output. However, FAIL and self diagnosis output take priority over the
internal switch status output.
1.2 Control Function Overview