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Help - SBus Generic Client Protocol
Overview
Generic client support is experiment at this time and is subject to change.
SAIA Ether-SBus
SAIA Ether-SBus (referred to here simply as "SBus") is the Ethernet version of the SBus protocol used by SAIA. The SBus client provides the ability to use the following SBus commands as a client:
- 2 - Read Flags
- 3 - Read Inputs
- 5 - Read Outputs
- 6 - Read Registers
- 11 - Write flags
- 13 - Write outputs
- 14 - Write Registers
The client is implemented in the following files:
- sbusudpclient.py
- SBusMsg.py
- ModbusDataLib.py
Standard Parameters
The following are the standard generic client parameters for this generic client.
| Item | Value | Description |
|---|---|---|
| protocol | sbusudp | Selects SBus protocol |
| type | genericclient | Selects genericclient |
| clientfile | sbusudpclient.py -d 1 | Specifies the name of the file used to implement the client. The parameter "-d" will specify a start-up delay in seconds. |
Example:
type = genericclient protocol = sbusudp clientfile = sbusudpclient.py
Client Parameters
| Item | Description | Valid Values |
|---|---|---|
| host | The name or IP address of the SBus server (PLC or field device). | Any valid host name or IP address (e.g. localhost, 127.0.0.1, etc. |
| port | The UDP port number of the SBus server. | This is normally 5050. |
| cmdtime | This is the delay time in milli-seconds between commands. | An integer greater than or equal to 0. |
| repeattime | This is the delay time in milli-seconds between repeating sets of commands. | An integer greater than or equal to 0. |
| retrytime | This is the delay time in milli-seconds between retrying commands in the event of an error. | An integer greater than or equal to 0. |
| timeout | This is the communications time-out milli-seconds. | An integer greater than or equal to 0. |
Example:
host = localhost port = 5050 repeattime = 500 retrytime = 2000 cmdtime = 500 timeout = 1000
Commands
| Item | Description | Valid Values |
|---|---|---|
| action | This is reserved for future use. | Must always be "poll". |
| stn | The SBus "station" parameter. | 0 to 255 |
| cmd | The SBus command code. | Any of the supported SBus commands. |
| remoteaddr | The server (field device) data table address to read from or write to. | 0 to 65,535 |
| qty | The number of data elements to transfer. | 1 to 128 for boolean addresses, 1 to 32 for register addresses. |
| datatype | The system data table memory type to read from or write to. | 'coil', 'inp', 'holdingreg', 'inpreg' |
| dataoffset | Data offset index. | Greater than or equal to 0. Must be less than the maximum address transferred for the selected datatype. |
Example:
&readflag = action=poll, stn=1, cmd=2, remoteaddr=10, qty=10, datatype=coil, dataoffset=0 &writeflag = action=poll, stn=1, cmd=11, remoteaddr=0, qty=10, datatype=coil, dataoffset=0 &readreg = action=poll, stn=1, cmd=6, remoteaddr=0, qty=4, datatype=holdingreg, dataoffset=0 &readinp = action=poll, stn=1, cmd=3, remoteaddr=0, qty=10, datatype=coil, dataoffset=10 &writeoutp = action=poll, stn=1, cmd=13, remoteaddr=20, qty=10, datatype=coil, dataoffset=10 &writereg = action=poll, stn=1, cmd=14, remoteaddr=19, qty=10, datatype=holdingreg, dataoffset=10 &readoutp = action=poll, stn=1, cmd=5, remoteaddr=0, qty=10, datatype=coil, dataoffset=20