AERCO Modbus Communications Manual - Manual (Page 73)

Chapter 4
MODBUS
Communication GF-114
Hardware Setup & Installation USER MANUAL OMM-0035_0C
05/18/12 AERCO International, Inc. • 100 Oritani Dr. • Blauvelt, NY 10913 • Ph: 800-526-0288 Page 73 of 200
EMS
MASTER
T+/
R
+
T-
/R
-
SHIELD
- +
RS
485
COMM
P/
O I
/O BOX
C
-MORE SLAVE
NETWORK BOILER
1
- +
RS
485
COMM
P/
O I
/O BOX
C
-MORE SLAVE
NETWORK BOILER
2
TO OTHER NETWORK
BOILERS
(3
–
32
)
(SEE NOTE
3)
RS485 PORT
Figure
4-
13
.
EMS Master Controlling C
-More Slaves
NOTES
:
1.
IF EMS MASTER CONTAINS
4-
WIRE RS
485
PORT
,
TIE THE TWO POSITIVE
(+)
AND NEGATIVE
(-)
LEADS TOGETHER AS SHOWN IN FIGURE
4-
11
,
DETAIL “A” 2.
IF EMS MASTER CONTAINS ONLY A RS
232
PORT
, A RS
232
-TO
-RS
485
CONVERTER WILL BE
REQUIRED
.
3.
THE LAST C
-MORE SLAVE ON THE RS
485
LOOP
MUST HAVE ITS TERMINATION RESISTOR
(TERM
)
TURNED ON
.
ALSO
, BIAS
(BIAS
1,
BIAS
2)
MAY BE
REQUIRED
. CHECK WITH THE EMS MANUFACTURER
.