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Chapter 2 Specifications
2 - 3
Remark
1) Transmission cycle means the data cycle from main unit to communication module regardless of the cycle from
master module to slave module. it is necessary to consider scan time, number of communication module, number of
set blocks, communication data size per block when you set the transmission cycle. It takes 25
㎲
per a byte when
HS link data transmits from main unit to master module. As it is based on serial communication. So, the number of
blocks per cycle is limited and if the load is above it, the cycle might be delayed more than you set. Calculation
formula is as below.
a) Add the bytes of block within 1000bytes.
pack1 number of bytes = (Block
1
data size+8) + (Block
2
data size +8) ... + (Block
pack1end
data size +8)
pack2 number of bytes = (Block
(pack1end) + 1
data size +8) + (Block
(pack1end) + 2
data size +8)...
+ (Block
(pack2end)
data size +8)
... packN number of bytes = (Block
(packN-1) + 1
data size +8) + (Block
(packN-1) + 2
data size +8)
... + (Block
(packNend)
data size +8)
Number 8 means the size of block information in here.
b) Calculate all of HS links transmission time. HS link cycle have to be set bigger than whole HS link transmission
time. At this time, if calculated transmission time of each pack is smaller than 10ms, transmission time of
applicable pack have to be calculated as 10ms.
All of HS links Transmission time = pack1 Transmission time + pack2 Transmission time + ...
+ packN Transmission time
pack1 Transmission time = pack1 number of bytes * 25
㎲
*1
+ main unit scan time + communication
module scan and margin (5
㎳
)
pack2 Transmission time = pack2 number of bytes * 25
㎲
*1
+ main unit scan time + communication\
module scan and margin (5
㎳
)
...
packN Transmission time = packN number of bytes * 25
㎲
*1
+ main unit scan time + communication
module scan and margin (5
㎳
)
c) The number of blocks which can be set per HS link cycle.
As shown below table, in case that the scan time of main unit is within 2ms and only one communication
module is equipped, the number of blocks which can be used for HS link cycle service.
HS link cycle
Data size of
each block
Number of
blocks
(Stations)
10
㎳
244 byte 1
20
㎳
244 byte 2
50
㎳
244 byte 5
100
㎳
244 byte 10
200
㎳
244 byte 20
500
㎳
244 byte 50
1s, 5s, 10s 244 by
e
64
10
㎳
4 byte 64
Example) The number of blocks which can be set per HS-link cycle
2) It is necessary to calculate lead time of transmitting depending on the number of blocks and data size
per block. Because data receiving cycle is same with 1) which take 25
㎲
to transmits per 1byte.