Automation Direct D0-DCM, Руководство пользователя

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MODBUS R
T
U
D0–DCM with
5–6
D0–DCM Using MODBUS
DL05/06 Data Communications Module, 1st Edition, 08/05
Some MODBUS masters do not allow you to specify the MODBUS data type and address.
Instead, you specify an address only. This method requires another step to determine the
address, but it is not difficult. Basically, MODBUS also separates the data types by address
ranges as well. This means an address alone can actually describe the type of data and
location. This is often referred to as “adding the offset”.
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 two categories for this purpose.
•
Discrete – X, GX, SP, Y, C, S, T, CT (contacts)
•
Word – V memory , Timer current value, Counter current value
In either case, you basically convert the PLC octal address to decimal and add the
appropriate MODBUS starting address (as required). The following tables show the exact
range used for each group of data.
For an automated MODBUS/Koyo address conversion utility, download the file
modbus_conversion.xls from the www.automationdirect.com technical support website
> Technical and Application notes> PLC hardware> Coummunications
> app note #
AN–MISC–010.
DL05 Discrete Data Types
PLC Memory Type
QTY (Dec.)
PLC Range
(Octal)
MODBUS Address
Range Access
Inputs (X) 256 X0 – X377 12049 – 12304 Read
only
Special Relays (SP) 512 SP0– SP777 13073 – 13584
only
Reserved – – 13585 – 20000
Outputs (Y) 256 Y0 – Y377 2049 – 2304 Read/
Write
Control Relays (C) 512 C0 – C777 3073 – 3584
Write
Timer Contacts (T) 128 T0 – T177 6145 – 6272
Counter Contacts (CT) 128 CT0 – CT177 6401 – 6528
Stage Status Bits (S) 256 S0 – S377 5121 – 5376
Reserved – – 6529 – 10000
DL05 Word Data Types
Registers
(Word) QTY (Dec.)
PLC Range
(Octal)
MODBUS 40001
Address Range
MODBUS 30001
Address Range Access
V Memory (Timers) 128 V0 – V177 40001 – 40128 30001 – 30128 Read/
Write
V Memory (Counters) 128 V1000 – V1177 40513 – 40640 30513 – 30640 Read/
Write
V Memory (Data
Words) 3072 V1400 – 7377 40769 – 43840 30769 – 33840
Write
If the Host Software
or Master Requires
an Address ONLY