UM-0085-B09
DT80 Range User Manual
Page 367
RG
•
Ensure that there are no other Modbus master devices on the same serial network as the DT80. (For a TCP/IP
network multiple Modbus master devices can be present.)
•
If transactions are failing intermittently, electrical noise may be disrupting the network. If this cannot be rectified
then it may help to use the
RT
n
channel option to tell the DT80 to retry failed transactions a few times.
If the
MODBUS
channel is reliably returning values, but the values seem to be wrong, then check the following:
•
Make sure you have specified the correct register number. Be careful of "off by one" problems, as some device
documentation specifies 0-based protocol addresses, rather than the 1-based register numbers used by the
R
channel option.
•
Has any required scaling factor or span been applied correctly? Double check the device documentation.
•
For 32-bit integer or floating point quantities be sure to specify the correct data format option, e.g.
MBF
if the
device returns an IEEE-754 floating point value, or
MBL
for a long integer.
•
For 32-bit quantities, it is also quite possible that your device may require the
MBR
option as both "straight" and
"reversed" word ordering are widely used.