User`s manual
Western Reserve Controls 1782-JDM User’s Manual
PUB 24.0
21
2. Rx Data Length: Maximum number of bytes expected from the remote ModBus device.
Note that the DeviceNet produce length will read this length + 2.
3. Tx Data Length: Maximum number of bytes to be sent to the remote ModBus device.
Note that the DeviceNet consume length will read this length + 1.
4. ModBus Baud rate: The communications speed of the RS232 or RS485 link.
5. DeviceNet Baud rate: The selection of the baud rate is independent of any other
parameter.
6. ModBus Timeout: The amount of time the JDM waits for a command response from a
ModBus device before it declares an error due to a lack of response from the device. A
value of 0 indicates that this feature is not active.
During while waiting for the ModBus response, if polled, the JDM will return a poll
response with the “waiting” bit set.
7. Output Fault Action: Selection to determine whether each output will hold its last state or
transmit the ModBus string identified in the next parameter upon a device fault.
8. Output Fault Value/String: The message string the JDM will output after a Fault, if Fault
Value is selected above (hold last state is not selected). The default is no message. This
message is sent in “little endian” format.
9. Output Idle Action: Selection to determine whether each output will hold its last state or
transmit the ModBus string defined in the next parameter if the Master issues an Idle
Command.
10. Output Idle Value/String: The message string the JDM will output after an Idle
Command, if Idle Value is selected above (hold last state is not selected). The default is
no message. This message is sent in “little endian” format.
11. Serial Communications Framing Format: Selects which format of communications
protocol is used, with the valid selection indicated.
Note: “Little Endian” format means that the data is formatted such that each 2-byte word of
data has the least significant byte in the low order byte of that word and the most
significant byte in the high order byte of that word. This is opposite of the actual ModBus
string itself. This is done to facilitate the host software program in extracting “word”
integer or register data without having to re-order the individual bytes.