FPΣ User's Manual
8.7 PLC Link
241
Calculation example 4
Conditions: All stations have been added to an 8-unit link. Highest station number = 8. Relays
and registers have been evenly allocated. Scan time for each PLC: 5ms.
Ttx = 0.096
Pcm (per station) = 23 + (8 + 16) × 4 = 119
Tpc = Ttx × Pcm = 0.096 × 119 ≈ 11.43ms
Ts (per station) = 5 + 11.43ms = 16.43ms
Tlt = 0.096 × (13 + 2 × 8) = 2.79ms
Given the above conditions, the maximum value for the transmission time (T) of one cycle will be:
T max. = 16.43 × 8 + 2.79 + 5 = 139.23ms
Calculation example 5
Conditions: All stations have been added to a 2-unit link. Highest station number = 2. Relays
and registers have been evenly allocated. Scan time for each PLC: 5ms.
Ttx = 0.096
Pcm (per station) = 23 + (32 + 64) × 4 = 407
Tpc = Ttx × Pcm = 0.096 × 407 ≈ 39.072ms
Ts (per station) = 5 + 39.072 = 44.072ms
Tlt = 0.096 × (13 + 2 × 2) ≈ 1.632ms
Given the above conditions, the maximum value for the transmission time (T) of one cycle will be:
T max. = 44.072 × 2 + 1.632 + 5 = 94.776ms
Calculation example 6
Conditions: All stations have been added to a 2-unit link. Highest station number = 2. 32
relays and 2 register words have been evenly allocated. Scan time for each PLC: 1ms.
Ttx = 0.096
Pcm (per station) = 23 + (1 + 1) × 4 = 31
Tpc = Ttx × Pcm = 0.096 × 31 ≈ 2.976ms
Ts (per station) = 1 + 2.976 = 3.976ms
Tlt = 0.096 × (13 + 2 × 2) ≈ 1.632ms
Given the above conditions, the maximum value for the transmission time (T) of one cycle will be:
T max. = 3.976 × 2 + 1.632 + 1 = 10.584ms
NOTE
• In the description, "stations that have been added" refers to stations which
are connected between station no. 1 and the highest station number and for
which the power supply has been turned on.
• Comparing examples 2 and 3, the transmission cycle time is longer if there
is one station that has not been added to the link. As a result the PLC link
response time is longer.
• The SYS1 instruction can be used to minimize the transmission cycle time
even if there are one or more stations that have not been added to the link.
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