YZ Systems Milton Roy • 201 Ivyland Road • Ivyland, PA • USA • 18974 • P: 281.362.6500 • www.yzsystems.com
NJEX ZEO Version 04/13/2021
Page 89
Communication Settings
Protocol
Modbus
Data Framing
Modbus RTU
Slave Address Range
0-247, 0 = Modbus Disabled
Baud Rates
1200, 2400, 4800, 9600, 19200, 38400, and 56000
Number of Data Bits
7 or 8
Parity
None, Odd, Even
Stop Bits
1 or 2
Serial Communications
Redundant RS-485 2 Wire
N-400 Modbus Function Support
Code
Function
Description
1
Read Coil Status
Reads the ON/OFF status of discrete outputs (coils)
3
Read Holding Registers
Reads the binary contents of holding registers
5
Force Single Coil
Forces a single coil to either the ON or OFF state
6
Preset Single Registers
Presets a value into a single holding registers
16
Preset Multiple Registers
Presets values into a sequence of holding registers
Boolean Registers
The Boolean data type can be used for status or control. The discrete outputs or “coils” as defined
by the Modbus specifications are read/write registers. This ON/OFF data type can be
manipulated using Modbus functions 1 and 5.
The valid address range for this data type is 00001 to 09999.
Function 1
allows reading a single coil per query
Function 5
allows writing single or multiple coils per query.
Control Functions
The control functions available via Modbus are listed below. The registers are accessed using
Modbus functions 1 and 5. The master device can initiate a state change by setting a control coil.
The N-400 Controller will clear non-toggle type coils to acknowledge the state change has been
acted upon. Toggle type coils hold their current state until changed either locally or remotely. Coil
00006 determines whether a remote inhibit can be initiated by a contact closure (local) connected
to the inhibit inputs on the controller or by Modbus coil 00007 (remote). Coil 00010 is used to
save all the current parameters to the controller EEPROM.
Address
Access
Descriptions
00001
Read/Write
Write '1' to Start/Stop the system; always reads '0'
00002
Read/Write
Write '1' to start/stop a Verometer fill; always reads '0'
00003
Read/Write
Write '1' to Toggle between Proportional-to-Time and Proportional-to-
Flow Modes; always reads '0'
00004
Read/Write
Write '1' to reset the measured injection rate; always reads '0’
00005
Read/Write
Write '1' to reset the odorant injec
ted totalizer; always reads '0’
00006
Read/Write
MODBUS Remote Inhibit Control Enabled (1); Local Remote Inhibit
Control (0)
00007
Read/Write
MODBUS Remote Inhibit On (1), Off (0)
Appendix C: N-400 Modbus Specifications
