Field Device Messages

Overview:

Field data display shows the actual messages which are transmitted between the HMI server and the field device server acting as the source of the data. The field device may be a PLC or other similar controller.

HMIServer comes in two forms - client and server. With the client version HMIServer is the client (master) and the field device is the server (slave). With the server version, HMIServer is the server (slave) and the field device is the client (master).

The request column shows the messages from the protcol client (master) to the server (slave). The response column shows the replies from the server (slave) back to the client (master).

Modbus/TCP Protocol

"tid" = Transaction ID. "uid" = Unit ID. "func" = Modbus function. "addr" = Modbus data table. "qty" = number of Modbus data table addresses. "data" = data (in a response to a write request this may be the number of addresses written). All items correspond to the Modbus protocol definitions.

Ether S-Bus Protocol

"telattr" = Telegram attribute. "msgseq" = Message sequence. "stnaddr" = Station address. "cmd" = Command code. "addr" = data table address. "data" = Data. "acknak" = Acknak code.

Request

Response