This page sets up the network address and optional device parameters for a remote Modbus/TCP device that will be linked to for remote input and/or output (via the client read and client write maps). The local device acts as a Modbus master to the remote devices listed below.
Device #
IP Address
System Name: 
Unit (optional)
Swap Double Registers Connection Status
Default Poll Period
Seconds
Quick Help

Device number simply shows you where you are on the device list. Click "next" and "prev" to scroll through the list.

Remote Modbus/TCP devices to be accessed by this device are specified here. Enter the IP address of the remote device, a name to reference in other pages, a unit number, poll rate, and check "swapped" if appropriate. Then click "update".

The term "swapped" only applies to double or float formats. Modbus registers are, by definition, 16 bits of data per register. Access to 32-bit data, either 32-bit integer ("double"), or IEEE 754 floating point ("float"), is supported by the use of two consecutive registers. Modbus protocol is inherently "big endian", therefore, Modbus by the Module defaults to having the high order register first for double and float. If the low order register comes first on the device being accessed, check the "swapped" box.

If you have "swapped" turned around, you will quickly recognize it. If floating point data is reversed, a 1.0 becomes 2.2779508e-41, which simply rounds to zero. The pattern is not as predictable as the 1.0 example would suggest. A floating point 1.1 becomes negative 107609184. If 32-bit integer data is reversed, 1 becomes 65536.

Connection status will show a non-zero error code if there is a socket error. Possible errors include:

-104 Connection reset by peer
-111 Connection refused
-113 Connection aborted
-114 Network is unreachable
-116 Connection timed out
-118 Host is unreachable
-119 Connection in progress (means unsuccessful connect attempt, still trying)