SICK Encoder to SIEMENS PLC interface?

James T

Member
Join Date
Oct 2003
Posts
2
Hi,

I am looking to connect an Incremental Encoder to a PLC and have never done this before! I am experienced in using Digital IO, PLC Bits, Counters, Timers etc but have never incorporated an Encoder to a PLC.

The details of the hardware are as follows:

SICK encoder with the following interface:

TTL / RS422, 6 Channel (4V....6V) or (10V....30V)

or

HTL/ push, pull, 3 Channel (A,B,Z) (10V....30V)

Siemens S7-300 PLC range

I don't believe that the hardware is the problem its just that I don't know the standard approach, do I need a specific 'Counter Card'? or can I utilise spare IO. The resolution of the encoder I will use is going to only be 120 pulses per revolution and will equate to 2.5mm accuracy which is all I need, this then means an 18ms gap between pulses.

What I want to achieve with the PLC is just count down a number of pulses from the encoder from a known start position and then signal a reject cylinder.

Do I really need all the channels? a A, b B, Z?

Please can you help

Best Regards,

JT
 
I'm a little conservative when it comes to encoder inputs so I would use a counter card for this. The FM350-1 is a two-channel counter that is pretty reasonably priced.

When you say 18 msec I assume that means 18 msec between leading edges of one channel. To consistenly pick us a pulse you would need to make sure all the delays in the system (I/O module response, plc scan time, etc) add up to less than 9 msec, a pretty tall order. You could save a couple of bucks and go with an interrupt module, but I would stick with the counter.

What signals you use depends on how much noise and drift you can live with. If you have the signals and it doesn't cost you much to run them, run A, /A, B and /B. This will give you bidirectional decoding and good noise immunity. I would also go with the HTL signals to get the better signal to noise ratio.

Hope this helps.

Keith
 
Keith,

Thanks for the info, I will look into the FM350-1, I guess since it is 2 channel I will be able to look at both A /A, B /B as you advise.

I will also use the HTL to reduce the risk of noise.

I am unsure of what the cheaper option of an interrupt card is though can you explain or do you have a model type?

Thanks Again,

James
 
James-
When I say the FM350-1 is a two-channel counter I mean it is capable of full encoder interface for two encoders. However, I was wrong on that. It is actually a single channel counter. It will accept A, A/, B and B/ for one encoder.
I'm not really recommending you use the input interrupt method for counting. It's just another option. You can use a 6ES7 321-7BH00-0AB0 input module to generate interrupts. When you get an interrupt the plc will automatically run OB40. You will need to decode a mask in software to let you know what created the interrupt and then you will need to act accordingly. this is probably penny wise and pound foolish as you will most likely burn more money in development time using the interrupt method than the hardware cost of the counter. I just thought I woiuld toss that out and let you think about it.

Keith
 
Hi

We are using a 'interrupt IQ card 'and works fine
type 6ES7 321-7BH00-0AB0

The encoder is a 512 points per revolution and 1 point is 1 cm
time between pulses is about 20 msec

You only need A en B channel if you need to know direction of movement

Greetings

Eric
 
Biltong

Aikona hi,you think all the Rooineks (rednecks) know what Biltong is?
For all you Americans it is the best beef jerky in the world/
Go Boks go.

Steve
 

Similar Topics

Hello all, Let me start by saying that although I have been working with PLCs for 20+ years I am very (as in brand) new to the Siemens world (my...
Replies
3
Views
3,931
Hi all, been working on replacing an Ethernet/IP Sick encoder on our system. When try to push an IP address using Bootp/DHCP I'm able to find...
Replies
0
Views
1,272
Hi all, I've a fun one for you tonight... I've got a ControlLogix PLC (running v17). I've got a PowerFlex 525 drive with the Encoder Card added...
Replies
1
Views
1,920
Might anyone have a pinout of a SICK programmer (PGT-10-S) for use with an M23 adapter?
Replies
3
Views
2,103
Has anyone setup one of these? Ive followed the operating instructions but i getting a Connection type (Multicast/Unicast) not supported, error...
Replies
18
Views
8,517
Back
Top Bottom