2/17/2016 2:42 AM | |
Joined: 9/27/2006 Last visit: 9/10/2024 Posts: 12282 Rating:
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Hello jryu; As-I (Actuator Sensor-Interface bus) is a digital communication link that powers up and transmits on/off signals between an AS-I master and AS-I sensors or actuators (for example your valves). Newer profiles have been added in recent versions that support some analog signalling and Safety Integrated. Much information, videos and training material can be found on the main AS-Interface website: http://www.as-interface.net/?lang=en Here is a basic document on AS-I from Siemens, which I will resume quickly in the next few lines:
https://support.industry.siemens.com/cs/ww/en/view/1171856
As far as hardware is concerned, you would need: - an As-I master, either a CP 343-2 (on the main rack of the CPU) or a DP-As-I link, a Profibus-DP slave to As-I master interface, for example; - Asi cable, generally a flat, profiled 2-wire yellow cable designed for vampire-connection to AS-I slaves; - an As-I power supply, producing 30 VDC; the As-I cable carries this power to the AS-I slaves (24 VDC) and uses the extra 6 V DC as a carrier to modulate a digital signal, the As-I exchange data; - an AS-I address programmer, if your slaves do not support auto-addressing by a master (not necessary if your slaves do); - assorted As-I slaves (there are many types and forms of these); deepending on the As-I version selected, up to 31 or 62 slaves can be connected to a master. This equipment (cable, power supply...) is all available from Siemens, but also from various other manufacturers on the market. For information please open the Products tab in the AS-interface.net link proposed earlier. As-I buses run for 100m, but this can be extended with repeaters or extenders, while the maximum number of slaves per bus is fixed limit. Addressing of the slaves in the master is quite easy: the master reserves an area of 16 bytes for the slave data; the first nibble (4 bits, half of a byte) serves for diagnostics of the bus, the next 31 nibbles of data are associated to each slave on the bus as addressed. Extended addressing for 62 slaves is explained in the manual. Here are a few more documents from Siemens on the CP 343-2 AS-i master, and some Applicatioon notes that propose functions to simplify crecoivering data from the slaves and diagnostic the bus:
https://support.industry.siemens.com/cs/ww/en/view/5581657
As-i interface library for S7 AS-i masters https://support.industry.siemens.com/cs/ww/en/view/51678777
https://support.industry.siemens.com/cs/ww/en/view/50897766 Finally, to close the loop, here is an AS-I document from ifm Electronics, who manufacture your valves, so you can see how they fit in any AS-I bus, with Tips and Tricks for users of As-i.. Hope this helps, Daniel Chartier |
Last edited by: dchartier at: 2/17/2016 2:43:31 AMLast edited by: dchartier at: 2/17/2016 2:46:00 AMLast edited by: dchartier at: 08/03/2022 00:07:15 |
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2/17/2016 10:16 PM | |
Joined: 9/27/2006 Last visit: 9/10/2024 Posts: 12282 Rating:
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Hello jryu; Sorry for the long reply, I misunderstood your requirements. What type of valves are you controlling over As-i, digital (like solenoid valves, on/off) or analog (modulating positioner)? What make and model? Which As-I address did you attribute to the first valve, the one you control? What does your configuration look like? I have opened the AC141x configuration over Step 7 manual, found on this ifm download page: http://www.ifm.com/ifmus/web/pdownloads050_010_050.htm Does your configuration resemble the attached screencapture? If so, you are accessing 4 words of analog output over AS-I. By sending 16#w#100 to PQW 256, you are sending the binary message 0000 0001 0000 0000. Then you send 16#w#0 to PQW256, so a binary signal pattern of 0000 0000 0000 0000. So only bit 8 changes between the 2 messages. I would like to know the As-I address to find out the relationship between this single bit change and the controlled valve, and see if there is an endian problem to be checked (checking whether there is a byte-swapping to be processed in your message).. Next, what address are you using for the second valve? Hope this helps, Daniel Chartier |
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