
35/42
SHEETDESCRIPTIONDESIGN DATE EDIT
01 Mutai Newl
re
istered
TITLE: Additional explanation of
PROFIBUS-DP Master function
(I/O Module Assignment function)
B-62924EN/04-1
FANUC LTD.
02.10.7
DRAW.NO.
With the following procedure, the slaves are divided into several groups.
<1> Add N_slot and SIZE respectively for each communication slave station in
ascending order of slave numbers. Each time N_slave, N_slot and SIZE for a slave is
added, substitute the cumulative number of communication slave stations (N_slave),
the number of slots (N_slot) and the DI/DO data size (SIZE) in expression (A) and
check whether the condition is satisfied.
<2> Increase the values of N_slave, N_slot and SIZE and obtain the maximum values of
N_slave
max,
N_slot
max
and SIZE
max
that satisfy the condition for expression (A).
<3> When the value of the left-hand side exceeds C, clear the values of N_slave, N_slot
and SIZE once. Start calculation from step <1> as the second group.
<4> Perform steps <1> to <3> for all communication slave stations and count the number
of slave group (n).
Thus, the data refresh time is obtained roughly as follows:
n × 8 msec
Example of calculating the data refresh time
[Conditions]
• CNC model: 16i/18i/21i-A/B
• Communication slave station settings for the master function:
- Slave No. 3: N_slot=1, SIZE = 122/122
- Slave No. 4: N_slot=1, SIZE = 122/122
- Slave No. 5: N_slot=1, SIZE = 122/122
- Slave No. 6: N_slot=1, SIZE = 122/122
[Calculation]
• First group
- Calculation for slave No. 3 and 4:
37×2 + 8.6×(1+1) + 1.3×(244+244)=726 <750
→ N_slave, N_slot and SIZE indicate the maximum values.
Slave No3 and 4 are first group.
- Calculation for slave No. 3 to 5:
37×3 + 8.6×(1+1+1) + 1.3×(244+244+244)=1088 >750
→ The values of N_slave, N_slot and SIZE should be cleared.
• Second group
- Calculation for slave No. 5 to 6:
37×2 + 8.6×(1+1) + 1.3×(244+244)=726 <750
→ Slave No 5 and 6 are second group. and calculation for all
communication slave stations is complete. Thus, the slave
group (n) is determined to be 2.
Thus, the data refresh time is 16 msec for this example.