mflux_gamblej

old SRM1 and SRT2, whats the modern currently produced equivalent?

7 posts in this topic

I have been using some older SRM1 PLC master units with several remote terminals of the SRT2 product line.  I think they're great as you only need 4 wires between devices to transmit a lot of I/O.  I'm interested in using a modern PLC and peripherals on a new project soon though. Mostly I'm interested in setting up an HMI and assume that I'll need some newer hardware for that.

What is a modern equivalent currently produced remote terminal from Omron?  I found some remote terminals called DRT2 for sale online, but Its unclear if those are the newest.

Has anyone managed to use old SRT2 products with new Omron PLCs?  The old ones use 'compobus' which seems to be RS485 but it is likely proprietary to that era of Omron hardware.

I have a decent amount of compobus hardware here, as an alternate option, it might be nice to use the older remote terminals paired with a new PLC and HMI.

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SRM master for the CJ series plc's would be CJ1W-SRM21.

These are showing a stock item with Omron US.

gtsuport.

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SRT2 is old (Compobus-S), as you said.  DRT2 is DeviceNet, also a legacy network, and not compatible with SRT2.

Your HMI should be serial (if required on the SRM1) or Ethernet (preferred, for newer PLCs), it cannot be connected to those old device networks.

I still have an SRM1 and some SRT2 blocks in use in my Halloween display, but they are being retired soon.

If you are moving to newer PLCs, there are other networks at play, such as IO Link or EtherCAT, with a more modern capability.  But you're switching out the entire system that way, PLC and IO...

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12 hours ago, Crossbow said:

SRT2 is old (Compobus-S), as you said.  DRT2 is DeviceNet, also a legacy network, and not compatible with SRT2.

Your HMI should be serial (if required on the SRM1) or Ethernet (preferred, for newer PLCs), it cannot be connected to those old device networks.

I still have an SRM1 and some SRT2 blocks in use in my Halloween display, but they are being retired soon.

If you are moving to newer PLCs, there are other networks at play, such as IO Link or EtherCAT, with a more modern capability.  But you're switching out the entire system that way, PLC and IO...

thanks for some history regarding srt2, drt2.

So on newer PLC's there pretty much isnt remote terminal hardware now?  if thats the case its too bad, the reason being that those old SRT2 remote terminals are compact so you can use them inside smaller mounted boxes around your project instead of running 32 wires of i/o you can just run 4, and then connect up the i/o locally.  saves a lot of wire (and saves a lot of expensive conduit and connectors).  For example I have two SRT2 units a 8 out and a 4 in unit mounted on top of a robot to do the end effector controls.  It would have been many long wires to get to the box, but instead its 4 wires and that controls 2 vac generators, 2 vac sensors, and 6 air solenoids.

Id think there has to be some kind of modern equivalent to a remote terminal.  I would hope it is a small PCB maybe even with a honda style or similar connector on it where you can wire up like 32 wires or something, then there'd maybe be an ethernet port on it to talk ethercat or someting similar.  that'd be great and I imagine it could be very compact like the size of an arduino board.  but I dont see anything immediately in the omron catalog for example.

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I never said there was no current solution for remote I/O.  I said newer solutions would use different networks.  DeviceNet and Compobus-S are old.  There are hundreds of vendors offering different I/O solutions for the open networks.  If you cannot find an Omron I/O block that suits your needs, check www.ethercat.org and see who else makes one.  The primary device being used for remote I/O on newer Omron controllers is the NX-Series modular I/O system on EtherCAT.  You make your own terminal with a wide variety of input and output types to choose from.  As for one the size of an Arduino, I don't know of one.

Trust me, I am well aware of the benefit of remote I/O.  The whole reason I used SRM1 in my haunted house was the small terminal blocks and 4 conductor wiring.  

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I found the omron version of ethercat remote io it is called GX-ID1611

http://products.omron.us/item/compact-i-o/gx/gx-id1611

its $600.

the old SRT2 stuff can be bought for $25ea at the time of this posting

i guess if you're using ethercat then its good to have all the same bus? but its pretty sad that this remote terminal is larger than the compobus predecessor as it needs two address selector trim pots, two ethernet ports, and it also has a 24v terminal block to power the thing lmao this is not better tech.

Edited by mflux_gamblej

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EtherCAT is way better tech, it allows far more data at far faster speeds.  Size of hardware and price on aftermarket obsolete products has nothing to do with better tech.

I can use the NX-Series EtherCAT coupler to make custom nodes with whatever I/O I want, up to 63 modules per node address.  I can also do motion control and safety over EtherCAT.  EtherCAT can move thousands of words of data in milliseconds.  It is far superior to Compobus/S, DeviceNet, Profibus, etc.  Even DeviceNet and Profibus moved away from the serial networks and into EtherNet/IP and Profinet.

Compobus/S was a sensor network, used back in the day when PLC IOs were all wired to a main control cabinet, in order to save wiring.  It was a more cost effective solution for its day than DeviceNet.  In its first incarnation (SRT1) it didn't even support analog I/O.  It was made as a competitor to AS-Interface.

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