Table 2.2: Comparison of Types of Connections Topic
RS232C DeviceNet
Ethernet Controller Link
Unit Ease
Need to build own cable
[3] . Able to
purchase in whole set.
Able purchase in
whole set. Able to purchase
in whole set.
Cost Cheapest
since can custom made
according to operational
manual [3] . Expensive,
need purchase
software and DeviceNet
controller card.
Expensive, need
purchase cable from
detailer. Expensive, need
purchase software and
Controller Link Unit controller
card.
2.4 Type of header
In the CQM1H-CPU21 Programmable Logical Controller, there are total 38 type of header code. But in this project only use 1 type of header code in this project to read the
data from the CQM1H-CPU21 Programmable Logical Controller.
Since in this project only do for read data from CQM1H-CPU21 Programmable Logical Controller, thus, I will only choose from 8 types of memory read header codes
which are IRSR area read RR, LR area read RL, HR area read RH, PV read RC, TC status read RG, DM area read RD, EM area read RE, and AR area read RJ [9] .
These 8 types of header codes possess different application field, such as RD is using to read data memory area which is from DM0000 to DM 6559 [10]. For IRSR area read RR,
it is read only the IR and SR which means this header code able to read from IR016 to
IR243 and from SR244 to SR251. Table 2.3 shows the comparison between these 8 types of header codes, and their application field [9]:
Table 2.3: Comparison of Header Code for Read Purpose Header
Codes Application Memory Area
Advantages Limitations
RR From IR0000 to IR0255.
Total of 256 available
storing memory [11]. Direct information
from IO status.
Value depends on
IRSR [11] .
RL From LR0000 to LR0063.
Total of 64 available
storing memory [12]. Sharing memory area
when connect CQM1H-CPU21
with other types of PLCs.
Only used to share data between
CQM1H-CPU21 and other PLCs
[12] .
RH From HR0000 to HR0099.
Total of 100 available
storing memory [13]. Data store even after
the power of CQM1H-CPU21 is
turn off.
Cannot use as reset input for Keep 11
[13] .
RC From PV0000 to PV0511.
Total of 512 available
storing memory [14]. Able to read the
current values of timer and counter.
Only apply for timer and counter
present values PV [14] .
RG From TC0000 to TC0512.
Total of 512 available
storing memory [14]. Able to shows the
timer or counter flag directly.
Only apply for timer and counter
completion flag [14] .
RD
From DM0000 to
DM6655.
Total of 6656 available storing memory[10].
Able to manipulate value through Ladder
diagram programming.
Need additional rung step in ladder
diagram to set data of data memory
area.
RE
From EM0000 to Able to be used
Only apply in
EM6143.
Total of 6144 available storing memory [15].
freely. CQM1H-CPU61
[15] .
Not available in CQM1H-CPU21
PLC.
RJ From AR0000 to AR0027.
Total of 28 available
storing memory[16]. Serve as CQM1H-
CPU21 PLC internal setting memory area.
Only used for
setting purpose.
2.5 Software Tools
