Automationdirect.com HX-ECOM Series - PLC Memory Supported for Client Operation

Ethernet Communications Modules, 3rd Edition, Rev. D
5-17
Chapter 5: MODBUS TCP for H0/H2/H4-ECOM100
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PLC Memory Supported for Client Operation
The actual equation used to calculate the address depends on the type of PLC data you are
using. The PLC memory types are split into three categories for this purpose.
• Discrete Inputs - GX, X, SP
• Discrete Outputs - GY, Y, CR, T, CT, S
• Word - Timer current value, Counter current value, Data Words
In either case, you basically take the Modbus address you are trying to target, subtract the
starting Modbus of that range, convert the result to octal and add the octal number to the
begining PLC address in the appropriate PLC range. See the conversion examples on the
following page. The following tables show the exact range used for each group of data.
NOTE: For an automated Modbus/Koyo address conversion utility, download the file
Modbus_conversion.xls from the www.automationdirect.com website.
Discrete Data Types*
PLC Memory Type
Qty
(Dec.)
PLC Range
(Octal)
Modbus
Address Range
Access
Global Inputs (GX)
2048
GX0 – GX1746
GX1747 – GX3777
10001 – 10999
11000 – 12048
Read Only
Inputs (X)
1024 X0 – X1777 12049 – 13072
Special Relays (SP)
512 SP0 – SP777 13073 – 13584
Reserved
– – 13585 – 20000
Global Outputs (GY)
2048 GY0 – GY3777 1 – 2048
Read/Write
Outputs (Y)
1024 Y0 – Y1777 2049 – 3072
Control Relays (CR)
2048 C0 –C3777 3073 – 5120
Timer Contacts (T)
256 T0 – T377 6145 – 6400
Counter Contacts (CT)
256 CT0 – CT377 6401 – 6656
Stage Status Bits (S)
1024 S0 – S1777 5121 – 6144
Reserved
––
–– 6657 – 10000
* Refer to your PLC user manual for the correct memory mapping size of your PLC. Some of the addresses shown above might not
pertain to your particular CPU.
Word Data Types*
Registers (Word)
(V-Memory)
Qty
(Dec.)
PLC Range
(Octal)
Modbus
Address Range
Access
Timers
256 V0 – V377 40001 – 40256
Read/Write
Counters
256 V1000 – V1377 40513 – 40768
Data Words
256 V400 – V777 40257 – 40512
3072 V1400 – V7377 40769 – 43840
5903 V10000 – V23416 44097 – 49999
5361 V23417 – V35777 410000 – 415360
System Parameters
128
1024
V7600 – V7777
V36000 – V37777
43969 – 44096
415361 – 416384