BusWorks® Model 989EN U
ser’s Manual Modbus TCP/IP Digital I/O & Counters
_________________________________________________________________________________
_______________________________________________________________________________________
Acromag, Inc. Tel:248-295-0880 Fax:248-624-9234 Email:
42
0xxxx Coil Registers are mapped to 42xxx Holding Registers
1xxxx Input Status Registers are mapped to 41xxx Holding Registers
3xxxx Input Registers are mapped to 43xxx Holding Registers
For 3xxxx Input Registers, the format of the registers is identical and you
only need to offset your address by 43000. For example: if you want to read
Input Register 1 through the Holding Registers, you would use the “Read
Holding Registers” function with an address of 43001.
For the 1xxxx Input Status Registers, the return data is reformatted to match
the Holding Register format. For example: if you request the Input Status for
16 digital inputs, instead of getting 2 bytes returned with the 16 bits
representing the 16 digital inputs, you will get 16 separate words, each set to
either 0000H (OFF), or FFFFH (ON).
For the 0xxxx Coil Registers, reads are handled in the same way as the
1xxxx Input Status Registers. You can also write to the coil registers by
using the “Preset Single Register” function with an address offset of 42000.
Setting the data to 0000H will turn the coil OFF, while setting the data to
FF00H will turn the coil ON. Writing to multiple coils is not supported via
register mirroring, you must use the “Write Multiple Coils” function for that.
I/O values for 989EN units are represented by the following simple data
types for temperature, percentage, and discrete on/off.
Summary Of Data Types Used By 9xxEN Models
Data Types
Description
Discrete
(This Model)
A discrete value is generally indicated by a single bit of a
16-bit word. The bit number/position typically
corresponds to the discrete channel number for this
model. Unless otherwise defined for outputs, a 1 bit
means the corresponding output is closed or ON, a 0 bit
means the output is open or OFF. For inputs, a value of
1 means the input is ON (Active low near 0V), while a
value of 0 specifies the input is OFF or in its high state
(usually >> 0V).
Normalized
Data Count
A 16-bit signed integer value is used to represent
20000
counts for bipolar input ranges and 0-20000 counts for
unipolar input ranges. For example, -1V, 0V and +1V are
represented by integer values
–20000, 0, and 20000 for
bipolar devices, respectively.
Temperature
A 16-bit signed integer value with resolution of 0.1
C/lsb
represents the range of a TC type measured in degrees
C. For example, a JTC type has a range of -210 to 760C,
which read -2100 to 7600 counts within the data register
respectively.
MODBUS
REGISTERS
Register Mirroring
Data Types
