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119
Message Communications Characteristics
Section 7-2
response message being sent or the message being received from another
node may be destroyed. Always perform message communications at inter-
vals longer than the message communications time and use message instruc-
tions (SEND, RECV, CMND, and IOWR). Never send messages to any one
node at intervals less than the message communications time.
If send or receive messages are destroyed, the error record will be placed in
the error history of the Master Unit. If an error occurs, read the error history
using the FINS command or monitor the error history from the Configurator.
The following equation can be used to calculate the approximate message
communications time.
Message communications time = Communications cycle time
×
((No. of mes-
sage bytes + 15) ÷ 6 + 1)
The number of message bytes is the number of data bytes following the FINS
command code. The communications cycle time depends on whether remote
I/O communications are being used.
Message
Communications
Only (Remote I/O
Communications Not
Used)
Message communications time = 2 (see note) + 0.11 × T
B
+ 0.6 (ms)
T
B
: Baud rate (500 kbps: T
B
= 2; 250 kbps: T
B
= 4; 125 kbps: T
B
= 8)
Note The communications cycle when remote I/O communications are not being
used is 2 ms.
Message
Communications with
Remote I/O
Communications
Communications cycle time = (Communications cycle time for remote I/O
communications only) + 0.11 × T
B
+ 0.6 (ms)
T
B
: Baud rate (500 kbps: T
B
= 2; 250 kbps: T
B
= 4; 125 kbps: T
B
= 8)
Note The above equations can be used to find the approximate message communi-
cations time, but not the maximum time. The message communications time
will depend on the frequency of the message communications, the load on the
remote node, the communications cycle time, and other factors. For any one
Master Unit, the message communications time may be greatly increased due
to heavy loads.
Summary of Contents for E5ZN-DRT
Page 3: ...iv ...
Page 5: ...vi ...
Page 9: ...x ...
Page 15: ...xvi EC Directives 6 ...
Page 83: ...68 Ladder Programming Examples Section 4 5 ...
Page 123: ...108 Sending Explicit Messages Section 6 5 ...
Page 135: ...120 Message Communications Characteristics Section 7 2 ...
Page 157: ...142 Index Unit status 57 85 user set allocations 43 61 V variable types C0 51 C1 51 C3 52 ...
Page 159: ...144 Revision History ...
Page 161: ...E5ZN DeviceNet Communications Unit Cat No H119 E1 01 OPERATION MANUAL ...