Emerson MONITORING OpenComms - Manual (Page 27)

Modbus Communications and Connectivity
21
Figure 7 Exceeding maximum specifications
The maximum specification may be exceeded if measures are taken to
drive or boost the EIA-485 communication line. Two wire EIA485
repeaters are available through the Liebert Corporation. SiteScan’s
“REPOPT” will work sufficiently for this application. Consult the
SiteScan price book for pricing schedule and alternative solutions.
5.4 Modbus Slave Functions
5.4.1 Data Type
The OpenComms NIC supports data in a register block as one of the
following types: Signed integer (16 bit) / Unsigned integer (16 bit) /
Signed long (32 bit); IEEE floating-point (32 bit); Null terminated
String.
A datum should consist of one or multiple registers. The leftmost byte
contains the MSB and the rightmost byte contains the LSB.
Modbus RTU Master
EIA-485 9600,N,8,1
Maximum of 32
devices with combine
cable length of 4000
feet
Modbus RTU Master
EIA-485 9600,N,8,1
Maximum of 32
devices with combine
cable length of 4000
feet
R
R