BusWorks® Model 989EN U
ser’s Manual Modbus TCP/IP Digital I/O & Counters
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The following table outlines the register map for the 989EN I/O processor.
The Modbus functions operate on these registers using the data types noted
above (except for the Reset Slave and Report Slave ID functions).
Not all programmable features of this device will include a corresponding
Modbus configuration register. Some functionality must be programmed via
the built-in web browser interface. For example, parameters related to
network communications do not have a Modbus register and are
programmed solely through the built-in web interface.
Ref
Addr.
Description
Data Type/Format
Coil Registers (0x References, Read/Write)
0
0001
Thru
0
0016
0-15
(0000-
000F)
16 Discrete
Outputs
(CH00-15)
(Default=0)
Data Format:
16-bit Unsigned Integer
Discrete Output Value. Addresses a
specific bit of a 16-bit word that
controls/monitors the ON/OFF status for
the corresponding output (gate signal of
the n-channel mosfet). 0=OFF; 1=ON.
The lsb is channel 0.
Note:
This signal corresponds
to the digital gate signal of the
n-channel output mosfet. Thus,
a read of this register may not
reflect the actual output level at
the drain of the mosfet for
certain conditions. You can
read the Contact Registers to
obtain the actual output state(s)
via closed loop feedback.
I/O will not operate without
excitation.
The bit position also corresponds to the
output channel number (i.e. output 0
uses bit 0 of the 16-bit word at address
0, output 1 uses bit 1 of the 16-bit word
at address 1, etc.) A set bit (1) means
the output is turned ON (sinking
current). A clear bit (0) means output is
turned OFF (open).
After reset, these registers read 0
(outputs OFF) and these registers are
not maintained in FLASH.
Ref
Addr.
Description
Data Type/Format
Contact Registers/Input Status (1x References, Read-Only)
1
0001
Thru
1
0016
0-15
(0000-
000F)
16 Discrete
Inputs 0-15
Data Format:
16-bit Unsigned Integer
Discrete Input Value. Addresses a
specific bit of a 16-bit word that flags the
ON/OFF status for the corresponding
input or tandem output. 0=OFF; 1=ON.
The lsb is channel 0.
Note:
This signal reflects the
actual state of the
corresponding input signal
relative to a 4.0V threshold, or
the drain of the tandem output.
This signal is active-low below
4V.
I/O will not operate without
excitation.
The bit position corresponds to the input
channel number for the port (i.e. input 0
uses bit 0 of the 16-bit word at address
0, input 1 uses bit 1 of the 16-bit word at
address 1, etc.). A set bit (1) means
input is ON (active-low < 4V threshold).
A clear bit (0) means input is OFF (high,
> 4V threshold).
Register Map
Model 989EN-4x16
