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7-51
7-9-6 Communications Response Time
The communications response times for communications with an Inverter via the RS-422/485 port of an
OMRON-made Communications Board are detailed below. Use this information as a reference when
deciding the number of Slaves to be connected to one network, and when considering the timing of input
and output signals.
H
Communications Time for One Message
•
A wide variety of programs for RS-422/485 communications can be created using the protocol macro
function. The communications times will vary according to the contents of the program.
•
In general, the communications time for one message can be calculated using the following formula.
Communications time = [Number of bytes in DSR message
×
10 (See note 1.)
×
(1/baud rate)
×
1,000 (ms)] + [Number of bytes in response
×
10
×
(1/baud rate)
×
1,000 (ms)] + [24
×
(1/baud rate)
×
1,000 (ms)] + send wait time setting n156 (ms) + protocol macro waiting time (See note 2.) (ms)
Note 1.
The reason that the number of bytes in the DSR message and response is multiplied by 10 is
because both the start bit and the stop bit require one bit each.
(1 byte = 8 bits) + (start bit: 1 bit) + (stop bit: 1 bit) = 10 bits
Note 2.
With RS-422/485 communications, set at least 20 ms as the protocol macro waiting time.
D
Calculation Example
The communications time required for one Slave in the protocol macro created in
7-9-7 Creating a Proj-
ect File
, can be calculated according to the following formula. (Baud rate = 19,200 bps.)
Communications time = [(DSR message to write data (13 bytes) + DSR message to read (8 bytes))
×
10
×
(1/19,200)
×
1,000 (ms)] + [(write response (8 bytes) + read response (7 bytes))
×
10
×
(1/19,200)
×
1,000 (ms)] + [24
×
(1/19,200)
×
1,000 (ms)
×
2] + [10 (ms)
×
2] + [20 (ms)
×
2] =
81.2 (ms)
Note
If there are N Slaves, the total communications time will be N
×
81.2 ms. Consequently, the more
Slaves that are used, the longer the communications time will be. If the number of Slaves is too
high, it is possible that the detection time of 2 s for communications time-over will be exceeded. In
this case, either disable the time-over detection function and use a different sequence to detect
communications errors, or increase the number of Masters thereby decreasing the number of
Slaves per Master.
H
I/O Response Time
•
The communications processing times for the Inverter are as follows.
S
Inverter communications input scan: 8 ms
S
Inverter communications output scan: 8 ms
S
Internal processing time for the Inverter: Approx. 20 ms
•
The I/O response times for the Inverter are illustrated in the following diagram.
Ladder program cycle time
Communications time
×
2
Inverter I/O scan
Internal processing for
the Inverter
Max. input re-
sponse time
Max. output re-
sponse time
Communications
Chapter 7
Содержание SYSDRIVE 3G3MV-A2001
Страница 1: ...Cat No I527 E1 04 USER S MANUAL SYSDRIVE 3G3MV Multi function Compact Inverter...
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Страница 3: ...USER S MANUAL Multi function Compact Inverter SYSDRIVE 3G3MVSERIES...
Страница 18: ......
Страница 23: ...Chapter 1 Overview 1 1 Functions 1 2 Nomenclature 1 3 New Features 1...
Страница 32: ......
Страница 33: ...Chapter 2 Design 2 1 Installation 2 2 Wiring 2...
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Страница 75: ...Chapter 3 Preparing for Operation and Monitoring 3 1 Nomenclature 3 2 Parameter Copy and Verify Function 3...
Страница 93: ...Chapter 4 Test Run 4 1 Procedure for Test Run 4 2 Operation Example 4...
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Страница 269: ...Chapter 9 Specifications 9 1 Inverter Specifications 9 2 Option Specifications 9...
Страница 293: ...9 25 D 3G3MV PRS2030V PRS3020V Four M4 holes for Inverter mounting use Three 5 dia holes Specifications Chapter 9...
Страница 294: ...9 26 D 3G3MV PRS2050V Four M5 holes for Inverter mounting use Three 6 dia holes Specifications Chapter 9...
Страница 297: ...9 29 D 3G3MV PRS1040V Three 5 dia holes Four M4 holes for Inverter mounting use Specifications Chapter 9...
Страница 303: ...Chapter 10 List of Parameters 10...
Страница 337: ...Chapter 11 Using the Inverter for a Motor 11...
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Страница 344: ...I527 E1 04...