Modbus ® Master / Slave Serial Port Menus; Eight / Sixteen Channel Modes - Honeywell HA71 Technical Manual

HA71 Digital Gas Controller
•
Display Alm YES forces the LCD to display the Bar Graphs
screen upon any new alarm. This feature is offered to satisfy
applications requiring channels in alarm to be displayed
automatically (all channels are displayed on the Bar Graphs
screen).
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2.3.4 Modbus Master / Slave Serial Port Menus
The system Modbus ® menu allows setting RTU Slave ID address,
Slave Baud rate and Parity for the comm2 slave Modbus
port (comm1 master port ID settings are per channel as described in
Section 2.2.4). This slave port may be used to transfer HA71 data to a
host device such as a PC, PLC, DCS or even another HA71. The slave
port is addressable, allowing many HA71 controllers to be connected
to a single RS-485 cable. Section 5
information describing how to interface to the HA71's Modbus
port.
The Mastr TO (master time out) and Mastr PR (master poll rate) menu
items affect the HA71's master Modbus
time in milliseconds before a communications error. Three consecutive
timeout errors must occur before a communication error is indicated.
This item is useful for optimizing throughput to the HA71 from other
slave RTU's. Poll Rate sets frequency of data requests to the RTU's in
milliseconds. This is useful when an RTU is limited in how fast it may
respond to consecutive data requests.
Figure 2-14. Modbus
HA71 Technical Manual
of this manual provides important
®
port. Time out sets length of
® Master/Slave Serial Port Menu

2.3.4 Eight / Sixteen Channel Modes

The final system menu allows setting the HA71 controller to accept
either 8 or 16 channels. If 8 channels are selected by this menu they
are channels 1-8 and 9-16 are disabled. One way HA71 cost is kept low
is Input / Output option PCB's are arranged into groups of 8 channels.
Therefore, users with less than 9 channels require only 1 PCB and
do not pay for I/O hardware for 16 channels. If more than 8 channels
are needed a second I/O option PCB may be required.
® serial
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slave
Figure 2-15. Eight/Sixteen Channel Mode Menu
2-11 Revision 3 (04/08)