Setup guide

Chapter 3 Driver and Protocol Objects
©
Automationdirect.com 3-57 Object Reference Manual
The Modbus object class uses Modbus Function Codes 01, 02, 03, 04, 05,
06, 15, and 16; and expects the remote I/O device to support these codes as
specified by Modbus. The driver can communicate with up to 247 Modbus
slave devices on each serial port.
The Maximum values per message settings specify the maximum number
of elements Lookout
Direct
attempts to read (
fc 1 – fc 4), or write
(
fc 15
and
fc 16
), in a single Modbus message. The default values
represent the maximum number of elements that the protocol can transmit
in a single message, and provides optimal speed. However, some devices
are not capable of handling the maximum number of elements, so you
should set the values according to the documentation for those devices.
If the Immediately write outputs option is ON, Lookout
Direct
immediately polls the device any time a value changes that is being written
out to the device. If it is OFF, Lookout
Direct
waits until the next scheduled
poll to write out changed values.
The Skip every… setting instructs Lookout
Direct
to not poll a device it has
lost communication with on every scheduled poll. Instead, Lookout
Direct
skips the device in the polling cycle accordingly. Once communications
have been reestablished, the device is polled on its regular cycle.
The Daniel option is device-dependent and instructs Lookout
Direct
to
treat holding registers as 32-bit IEEE floating values instead of 16-bit
values. If you set this flag, you must also set your hardware device to treat
holding registers as 32-bit floats—most devices do not support this option,
but Bristol-Babcock RTUs and Daniel flow meters do.