Stephen Luft
Lifetime Supporting Member
Most voltage ranges are limited, due to the coil voltage of the relays being used within the PLC. It wouldn't be as much of an issue on the upper end, but rather the lower end of the range in that the voltage drop for components like the relay and LED are subtracted from the voltage supply.
For instance, on our board there is a 1.5 volt drop across the LED and a minor drop across the relay. For a 24 volt system, we use a 24 volt coil relay which allows us to operate down to approximately 21 volts. On the maximum side, it isn't an issue with pulling in the armature of the relay, but with "frying" it.
With regards to scan time, in many PLCs, it is dependent upon the length of program. I know some of the more sophisticated controllers will allow you to determine what gets scanned and when. We aren't as slick. To improve scan rate, we offer jump if zero of functions whereby you can bypass a conditioned portion of code if it isn't in use.
Smart-PAK PLUS scan rate is 15ms/K, therefore a scan rate of 5 ms would require a compiled program size of 1/3. Number of rungs will depend on complexity, but I would say some where in the neighborhood of 100 to 150 rungs.
The analog chip within the Smart-PAK PLUS offers a 50KHz sample rate, but the update to the plc register is once ever scan. The resolution is 12 bit.
The idle current of 200 mA should be sufficient for the "combo board and main board. However, if the analog only board of the Smart-PAK PLUS is used it might require additional current in that it incorporates a switching power supply.
Ron's observations were good in terms of the Elite-2000 in that it can operate at a much wider voltage range and offers the 5 ms scan rate, but the analog board uses a triple output transformer for three different rail voltages, thus it would not be appropriate for a DC application.
With regards to the negative temperature range, will the application require a cold start or will it always be powered? If always powered, I would suggest a well insulated enclosure to retain the heat generated from the components. The main issue will be when you have to start when the temperature is below 0 C. Many of our customers incorporate a small heater or light bulb and "cheap" thermostat. Our standard operating temperater is 0-60C. A majority of the components are rated at industrial ranges of -40 to 85C. The only components that are not rated below zero are the processor, regulator, BBRam and EPROM. We can upgrade to a complete industrial temp board, but the lead times on these components have been terrible due to the whole RoHS transition.
It may come down to ordering a few different units and trying them in your application...especially if your requirements are critical.
Hope this helps,
God Bless,
PS...Ron, thanks for the props.
For instance, on our board there is a 1.5 volt drop across the LED and a minor drop across the relay. For a 24 volt system, we use a 24 volt coil relay which allows us to operate down to approximately 21 volts. On the maximum side, it isn't an issue with pulling in the armature of the relay, but with "frying" it.
With regards to scan time, in many PLCs, it is dependent upon the length of program. I know some of the more sophisticated controllers will allow you to determine what gets scanned and when. We aren't as slick. To improve scan rate, we offer jump if zero of functions whereby you can bypass a conditioned portion of code if it isn't in use.
Smart-PAK PLUS scan rate is 15ms/K, therefore a scan rate of 5 ms would require a compiled program size of 1/3. Number of rungs will depend on complexity, but I would say some where in the neighborhood of 100 to 150 rungs.
The analog chip within the Smart-PAK PLUS offers a 50KHz sample rate, but the update to the plc register is once ever scan. The resolution is 12 bit.
The idle current of 200 mA should be sufficient for the "combo board and main board. However, if the analog only board of the Smart-PAK PLUS is used it might require additional current in that it incorporates a switching power supply.
Ron's observations were good in terms of the Elite-2000 in that it can operate at a much wider voltage range and offers the 5 ms scan rate, but the analog board uses a triple output transformer for three different rail voltages, thus it would not be appropriate for a DC application.
With regards to the negative temperature range, will the application require a cold start or will it always be powered? If always powered, I would suggest a well insulated enclosure to retain the heat generated from the components. The main issue will be when you have to start when the temperature is below 0 C. Many of our customers incorporate a small heater or light bulb and "cheap" thermostat. Our standard operating temperater is 0-60C. A majority of the components are rated at industrial ranges of -40 to 85C. The only components that are not rated below zero are the processor, regulator, BBRam and EPROM. We can upgrade to a complete industrial temp board, but the lead times on these components have been terrible due to the whole RoHS transition.
It may come down to ordering a few different units and trying them in your application...especially if your requirements are critical.
Hope this helps,
God Bless,
PS...Ron, thanks for the props.
