Serial communication to CompactLogix 5370

jshiepe · Jun 6, 2012

We currently have a scale communicating to a SLC 5/05 over Remote IO (1747-SN). We are going to be changing out the 5/05 with a new CompactLogix 5370 series (1769-L33ER), which does not have an interface for RIO. The scale does have a serial output (9600 baud continuous output, 16 or 18 bytes transmitted in a 10-bit ASCII frame with 1 start bit, 7 data bits, 1 even parity bit, and 1 stop bit).

I've been looking for a quick and dirty way to get the scale communicating to the CompactLogix. Since there is no serial port on the CLogix, I assume the only way would be over Ethernet/IP, so started hunting around for serial to ethernet converters and was advised that the Digi One IAP is the product for the job. I've never worked with one of these before, so just curious if there are other options available or if this is the best way to go.

If the Digi One is the way to go, is the method for bringing the data into the CLogix a MSG instruction? Just looking for a little guidance on the PLC side as I've never interfaced a serial device like this before.

Thanks in advance for any assistance.

Jeff

hd_coop · Jun 6, 2012

jshiepe said:
We currently have a scale communicating to a SLC 5/05 over Remote IO (1747-SN). We are going to be changing out the 5/05 with a new CompactLogix 5370 series (1769-L33ER), which does not have an interface for RIO. The scale does have a serial output (9600 baud continuous output, 16 or 18 bytes transmitted in a 10-bit ASCII frame with 1 start bit, 7 data bits, 1 even parity bit, and 1 stop bit).

I've been looking for a quick and dirty way to get the scale communicating to the CompactLogix. Since there is no serial port on the CLogix, I assume the only way would be over Ethernet/IP, so started hunting around for serial to ethernet converters and was advised that the Digi One IAP is the product for the job. I've never worked with one of these before, so just curious if there are other options available or if this is the best way to go.

If the Digi One is the way to go, is the method for bringing the data into the CLogix a MSG instruction? Just looking for a little guidance on the PLC side as I've never interfaced a serial device like this before.

Thanks in advance for any assistance.

Jeff

I have never used a Digi One, but here are some other options to consider. We have used both here.

You could use a 1734-AENT + 1734-232ASC to add a serial port.

A Com-trol Devicemaster UP would also probably work, this wouldn't require any programming in the PLC. http://www.*******.com/pub/products/category/cid/80

JeffKiper · Jun 6, 2012

RTA Real Time Automation 435 or 460 line. The make things like this easy. 20 ~30 minues and you are up and running.

(8{)} ( .) · Jun 6, 2012

Use a WAGO 750-881 and write a simple protocol to extract the scale data. The WAGO supports all of the string manipulation instructions you'll need and you can program it in ST. The WAGO supports EthernetIP and can be easily integrated to the CLX EIP as I/O.

We've done several similar projects and I'd be glad to help you out.

Good Luck,

(8{)}

.)
(Yosi)

JeffKiper · Jun 6, 2012

If the system needs an HMI you could use a Red Lion and bring the data in to the serial port then parse the string out. That is not bad either. I have used both and I still stock both devices.

mellis · Jun 6, 2012

If you want to get this nailed down, manufacturer and model number of the scale would be a big help. Especially the model of any interface card used for the RIO communications.

The standard serial port or ethernet port on most scales I've worked with send ASCII string data which requires quite a bit of programming on the PLC end to interpret the strings into useable data.

You may just luck out and be able to replace the RIO interface in the scale with an Ethernet/IP interface. (Some Mettler-Toledo scales can do this) With Ethernet/IP you get data in tags instead of strings.

Alternatively, replacing the scale head is another reasonable option. They aren't cheap, but the cost of converters and additional programming may be even more.

jshiepe · Jun 6, 2012

Thanks to all so far for the replies.

The scales are Mettler-Toledo with the Panther display (don't have exact model # handy). We've investigated replacing them, but the department that would have to pay the bill can't justify it since there is nothing wrong with the scales.

I can look into swapping out the RIO interface board if that is an option. I'm trying to keep this low cost because these scales will eventually be integrated to a PC, and the serial output will work fine for that. So basically this is a temporary solution until the migration to the PC-based system takes place.

JeffKiper · Jun 6, 2012

There is only around $250.00 dollar difference between the RTA and the Red Lion Data station.
If this is only going to be a temporary system I would probably use the Red Lion Data Station and keep it after the project is done. This is one of my go to devices for communication protocols and bridging.

Either way you are under $1K for a solution.

Serial communication to CompactLogix 5370

jshiepe

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(8{)} ( .)

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jshiepe

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