AB HSCE2 Wiring Question

The AB HSCE2 is a high speed counter card with 4 physical outputs which are controlled directly by the card for immediate operation.

What I want to do is wire one of the outputs (which will be controlled by a quadrature encoder wired to the card) to the Z (hold) input for a pulse counter also on the card. This will let me hold the pulse counter value when the encoder reaches a specific count.

I'm an Mech. Eng. by education so my question is, can I just run a wire from the output to the input on the card or do I need some intervening fuse or resister or cap or something??????

Thanks

There are probably several people here with more AB knowledge than I have, but they haven't tackled this one yet, so I will. I have a manual for a 1746-HSCE module. I don't know if the HSCE2 is significantly different, so you should verify that everything I say here is applicable to your module.

According to my manual, the outputs on the 1746-HSCE are sinking outputs, so to connect an output to the Z input, you'll need a pullup resistor from DC+ to the Z+ input terminal. Connect the Z- terminal to DC-.

That should give you a change-of-state at the Z+ input when the counter reaches the preset value, but it may not do what you want it to. You said you wanted to treat the Z input as a 'HOLD' command to the counter. On a cursory look through my manual, I didn't see where you could configure the module that way. The Z signal from an encoder is normally a marker signal that occurs once per revolution of the encoder. It is most frequently used in a homing routine to get an axis back to a known position. The 1746-HSCE manual describes how to configure the Z signal as a 'RESET' command.

If it is possible to configure the Z signal as a 'HOLD' command, then you probably also need to configure the output to be ON for accumulated count values less than the preset and turn OFF when you reach the preset. This is because the pullup resistor will make the Z+ terminal show a voltage until the output switches on and provides a path to ground.

If you're going to use the Z signal as a 'HOLD' command, you'll also need some method to reset the counter. Perhaps the Limit Switch input, if the HSCE2 still has one.

This is probably pretty confusing, but maybe bumping it to the top of the list will encourage someone with experience on this specific module to set me straight.

I guess I should have included the specs on the input and output points for the HSCE2 (which appear to be different than the HSCE):

For the Z input in question:

Input voltage: 24 vdc (can also be 5vdc but I'm using 24)
Input Voltage Range: 10vdc to 30vdc
On-State Voltage (min): 10V
Off-State Voltage (max): 3V
Max Off-State Leakage: 100 microA
Input Current (max): 20 mA
Input Current (min): 6.3 mA
Nominal Input Impediance: 1500 ohms
Min Pulse Width: 475 nano-sec
Min Pahse Separation: 200 nano-sec
Max Input Freq: 1 MHz
Isolation from backplane: 1000 V
Isolation from Outputs: 500 V

For the high speed output in Question (which is listed as sourcing

Output Voltage Range 5-30 Vdc
Max On-State Output Current: 1.0Amp @ 60 deg C.
Max ON-State Voltage Drop: 0.5V
Max Off-State Leakage current: 100 microA
Isolation from backplane: 1000 V
Isolation from Inputs: 500 V


One concern I have is that the max off-state leakage for both sides is the same. If both are at or near this limit of 100 uA am I in danger of seeing a false transition on the input?

You said you wanted to treat the Z input as a 'HOLD' command to the counter. On a cursory look through my manual, I didn't see where you could configure the module that way. The Z signal from an encoder is normally a marker signal that occurs once per revolution of the encoder. It is most frequently used in a homing routine to get an axis back to a known position. The 1746-HSCE manual describes how to configure the Z signal as a 'RESET' command.

Click to expand...

For the HSCE2 the Z input can be programmed to perform one of several functions:

• No Preset - ignored
• Soft Preset Only (Internal bit used for marker function) Physical input ignored
• Store / Continue (Copies current count to register - flags SLC)
• Store / Hold / Continue (Same as above but Holds value when Z input high)
• Store / Preset / Hold / Resume - (Stores current count & flags slc, resets count to preset value and holds count until Z goes low again)
• Store / Preset / Start (Stores current count, flags slc, sets count to preset value and keeps counting)

This last option seems to mimic the traditional encoder Z channel functionality

Anyway, this is some more informaiton which seems to show that the HSCE and HSCE2 are definately different birds

It looks like they added quite a bit of additional functionality to the HSCE2.

You should be able to wire the sourcing output directly to the Z input. I would interpret the leakage current spec on the Z input to mean that you can connect any device with a leakage current of 100 microamps or less to the input. The HSCE2's output meets that spec.