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| 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". If your slave/server device only supports function codes 5 and 6 for writing, check the Use FC 5/6 box. The default function codes are 15 and 16, which are most widely used. You may have the system look up the IP address given a domain name. If the IP address is set to zero, an attempt will be made to find the host by name. You also have the option of specifying a non-standard port number. If port is left set to zero, 502 will be used. 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: 81 = Connection in progress (means unsuccessful connect attempt, still trying) | ||||||||
