Help Topics

Help Topics for SBPoll

Supported SBus Commands
Installation
Command Line Parameters
Sending Data
Return Codes
SBus Protocol
Using SBPoll
Polling performance measurement

SBPoll

Overview:

SBPoll is a simple SAIA Ether SBus command line client with the following features:

It can read from and write to a Ether SBus server.
It supports the most commonly used SBus client commands.
All parameters are configurable.
It can poll repeatedly, to allow load testing of a server.

Supported SBus Commands:

The following SBus commands are supported:

2 - Read Flags
3 - Read Inputs
5 - Read Outputs
6 - Read Registers
11 - Write flags
13 - Write outputs
14 - Write Registers

SBPoll will come as an archive file in "tar-gz" (most platforms) or "zip" (MS-Windows) formats. The MS-Windows version has the special new-line character combination (CR-LF) required by that platform, but is otherwise identical to the standard version.

Extract the archive file into the desired location. SBPoll doesn't care where you place it.

Installing Python:

This is the language support for Python which is required for SBPoll to run. SBPoll has been tested with version 2.5 and 2.6. Other versions may work but have not been tested. For Linux, Python is often already installed. If not, it can normally be installed from the distro's package manager. For MS-Windows, Python can be downloaded from http://www.python.org

Command Line Parameters:

Address, command codes, and other values are specified by means of command line parameters. If a parameter is omitted, its default value is used. The parameters are:

Ethernet Address Parameters

Parameter	Description	Default
h	Host name of the Ether SBus server	localhost
p	Port number of the Ether SBus server	5050
t	Receive time-out in seconds	60 (minimum = 1)

Note: -h (host). For SBPoll, this is the IP address or domain name.

SBus parameters

Parameter	Description	Default
c	Command	2
n	Station address	1
a	Address (SBus memory)	0
q	Quantity of addresses	1

Polling parameters

Parameter	Description	Default
r	Repeats. Number of times to perform the poll.	1
y	Delay time between repeats (in millseconds)	1
d	Data to send to the server.	0000
s	Silent mode. 'Y' or 'y' will suppress displaying data.	'n'

Note: Actual delay time is affected by the resolution of the operating system process scheduler.

Sending Data:

For commands 2, 3, 5, or 6, any data specified is ignored.
For commands 11, 13, or 14, data must be specified.
For commands 11 or 13, data must be 0 and 1 characters, in multiples of 8 characters. E.g. 00111010.
For command 14, data must be in hexadecimal with 8 characters per register. Hexadecimal values a to f may be in lower or upper case. E.g. 23aD0129

Return Codes:

The following command line return codes are defined:

Return Code	Description
0	No errors.
2	Bad command line.
3	Program was terminated from keyboard
4	Invalid data for SBus command.
5	Error communicating with host.
6	Invalid SBus parameters.

SBus Protocol:

SAIA SBus has a number of concepts similar to Modbus, but has several different characteristics.

Boolean addresses are known as inputs, outputs, and flags.
Registers are 32 bit signed integers.
Command codes are known as "commands" rather than "functions".
Reads and writes of boolean addresses are limited to no more than 128 addresses at a time.
Reads and writes of register addresses are limited to no more than 32 registers at a time.
The "station address" is equivalent to a Modbus "unit id".

Using SBPoll:

SBPoll is normally used from the command line. For Linux, the syntax is::


	./sbpoll.py (parameters)

For Microsoft Windows, the syntax is::


	c:\python26\python sbpoll.py (parameters)

A typical example is::


	./sbpoll.py -h 192.168.10.1 -p 5050 -t 10 -c 14 -a 6789 -q 1 -n 45 -d 0123abcd

The above example polls the Ether SBus server at UDP/IP address 192.168.10.1 using port 5050 and sets a time out of 10 seconds. It requests command 14 (write registers), address 6789, and station address 45. It requests to write data 0123abcd.

Another example is::


	./sbpoll.py -h localhost -p 502 -c 2 -a 6 -q 24

The above polls the server at localhost (located on the same computer as SBPoll), port 5050. It requests command 2 (read flags), flag address 6, quantity 24. It uses the default values for all other parameters.

Polling performance measurement:

When used to measure polling performance, silent mode should be enabled.
When more than one repeat is specified, extra information is displayed after polling is completed. This includes elapsed time, number of data elements transfered, and the data transfer rate.
When trying to measure maximum speed a large enough number of polls should be specified to allow measurement over several (e.g. 5 to 10) seconds in order to get an accurate reading.