Automation Direct D2-DCM, Руководство пользователя

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C–4
Using the D2–DCM with MODBUS
Data Communications Module, 2nd Edition, 2/03
Determining the MODBUS Address
There are typically two ways that most host software packages allow you to specify a PLC
memory location. These are:
D
By specifying the MODBUS data type and address.
D
By specifying a MODBUS address only.
Many host software packages allow you to specify the MODBUS data type and the MODBUS
address that corresponds to the PLC memory location. This is the easiest method, but not all
packages allow you to do it this way. The various MODBUS data types were presented
earlier, but they have been included again in the following table.
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.
D
Discrete – X, SP, Y, CR, S, T (contacts), C (contacts)
D
Word – V, Timer current value, Counter current value
In either case, you basically convert the PLC octal address to decimal and add the
appropriate MODBUS address (if required). The following tables show the exact equation
used for each group of data.
DL205 Memory Type QTY 1
(Dec.)
PLC Range
(Octal)
MODBUS
Address Range
MODBUS
Data Type
For Discrete Data Types .... Convert PLC Addr. to Dec. + Start of Range + Data Type
Inputs (X) 320 X0 – X477 2048 – 2367 Input
Special Relays (SP) 144 SP0 – SP137
SP540 – SP617
3072 – 3167
3280 – 3471
Input
Outputs (Y) 320 Y0 – Y477 2048 – 2367 Coil
Control Relays (CR) 256 C0 – C377 3072 – 3551 Coil
Timer Contacts (T) 128 T0 – T177 6144 – 6271 Coil
Counter Contacts (CT) 128 CT0 – CT177 6400 – 6527 Coil
Stage Status Bits (S) 512 S0 – S777 5120 – 5631 Coil
For Word Data Types .... Convert PLC Addr. to Dec. + Data Type
Timer Current Values (V) 128 V0 – V177 0 – 127 Input Register
Counter Current Values (V) 128 V1000 – V1177 512 – 639 Input Register
V Memory, user data (V) 1024 V2000 – V3777 1024 – 2047 Holding Register
V Memory, user data (V)
non–volatile 256 V4000 – V4377 2048 – 2303 Holding Register
V Memory, system (V) 106 V7620 – V7737
V7746 – V7777
3984 – 4063
4070 – 4095
Holding Register
If the Host Software
Requires the Data
Type and Address...