AERCO Control System (ACS)
CHAPTER 3
: Operation
Page 50 of 139
AERCO International, Inc.
•
100 Oritani Dr.
•
Blauvelt, New York 10913
11/22/2017
GF-131
Phone: 800-526-0288
OMM-0081_0F
3.6.3 MODBUS ADDRESS
The
MODBUS ADDRESS
option sets the ACS address when operating as a Slave on a
Modbus Network. The address can be set from 128 (default) to 247.
3.6.4 NETWORK TIMEOUT
When the ACS is operating in the Remote Setpt mode via Modbus, the
NETWORK TIMEOUT
option defines the maximum time (seconds) allowed before re-sending the setpoint information.
If the information is not resent within this time period, the ACS will default to its Failsafe mode of
operation set in the Configuration Menu and display “MODBUS TIMEOUT ERROR”. The
network timeout period is selectable from 005 to 240 seconds (Default = 060).
3.6.5 MODBUS PASS THRU
When enabled, the MODBUS PASS THRU option allows an EMS or computer, communicating
from the RS232 port, to access information from the boilers connected on the RS485 port of the
ACS. When enabled, it allows boiler monitoring and setup but not direct control of the boilers.
To enable writing to the boiler control, you must go to the Calibration Menu and enable
“PASSTHRU WRITE”.
RS485 (MODBUS) MENU
3.6
The ACS communicates with the connected AERCO network boilers via its RS485 (Modbus)
Port (485 B+ and 485 A-). Therefore, the RS485 Menu contains the options necessary to enable
communication between the ACS and the connected network boiler slaves. Each network boiler
on the Modbus network must be assigned a unique address to enable communication.
The RS485 Menu options are used to select the RS232 Baud Rate, Min./Max. Range of Slave
Addresses, Total Number of Networked Boilers, Type of Modbus Control and the Unique
Address for each Networked Boiler. Descriptions of these options follow.
The ACS can automatically detect boilers within the “”Min Slave Addr” and “Max Slave Addr”
range, or you can program the boiler addresses in the order desired. AERCO recommends
programming the addresses in the desired order. When programming the boiler addresses, set
the “Min Slave Addr” and “Max Slave Addr” to zero.
3.7.1 RS485 BAUD RATE
The
RS485 BAUDRATE
option
Sets the communication baud rate for the Modbus network
between the ACS and the Boilers connected to the RS485 terminals [B(+), A(-)]. Available
settings are 2400, 4800, 9600 (default), or 19200.
3.7.2 MIN SLAVE ADDR
The
MIN SLAVE ADDR
sets the Minimum Slave Address for the Boilers being controlled on the
RS485 (Modbus) Network when automatic boiler detection is desired; otherwise, leave set to
zero. Allowable entry range is 000 to 127 (default = 000).
3.7.3 MAX SLAVE ADDR
The
MAX SLAVE ADDR
Sets the Maximum Slave Address for the Boilers being controlled on
the RS485 (Modbus) Network when automatic boiler detection is desired; otherwise, leave set
to zero. Allowable entry range is 000 to 127 (default = 000).
3.7.4 NUMBER NETWK BLRS
This menu option sets the Number of Network Boilers connected to the ACS RS485 (Modbus)
