PWMOUT used with Parker VPL/Pulsar valve
Mark 7 years ago • updated by Ken Larsen 4 years ago • 7
Has anyone had any luck using the bi-directional PWMOUT with the Parker VPL/Pulsar valve proportional coils? I tried using one Bi output for two coils on a 4W/3P proportional valve(each valve section has 2 separate coils, 1 for shifting the valve in each direction) and did not have much luck and had to eventually use one output per coil (used on the positive return side). Was wondering if anyone else had a similar problem or am I missing something? Any help is greatly appreciated.
Customer support service by UserEcho
What module are you using (e.g. XA2), and how did you wire it? For biderectional PWMOUT mode, the coils must be wired in the same way as for bidirectional COUT mode, like this:
Mark, my experience with the Pulsar valves is to ensure the PWM frequency for the output is set correctly based on the Pulsar solenoid. This is usually 75 Hz or 33 Hz. The default settings for the PWM output channel under "Device Type" should be selected correctly for either 75 Hz or 33 HZ. If the frequency is not set correctly, then the Pulsar solenoids tend to work more like on/off than proportional.
I have tried to connect the Pulsar as shown above and with the PWM frequency set correctly and have had serious control problems. As a result I normally use one coil per output (which doubles the quantity of required outputs), but the problem goes away. I have had this problem on numerous occasions. I can try again, but I have spent many hours trying to solve this.
Our company predominantly uses TOC2 & Pulsar, but have also used the MDM system with them, and soon our first IQANDesign system with MD3 & XA2.
I've seen my share of problems around Pulsar, but never one you describe.
Some modules require the PWM/DOUT signals terminate with respect to GND (like the XT2), while others (like the TOC2) must return through the module's RET +/- lines.
Obviously you need to pay attention to solenoid voltage (black wires = 12V, brown wires = 24V), and PWM frequency as previously noted (although both coils should still work regardless).
Also note that you CANNOT put diodes of any type (zeners or rectifiers) across the coils, or problems will certainly abound. There is some literature out there to use them, but that's only for ON/OFF applications, and possibly some other manufacturers.
What about using the Pulsar valves with an MC42 or MC43? The instruction manual says there is an internal free wheeling diode which makes it unsuitable for use with the pulsar valves when using HS + LS, and if you use HS to ground it says this is unsuitable as well. Is it possible to use the Pulsar with these modules?
I have not personally tried using the MCx (MC41, MC42, MC43) modules on Pulsar, specifically due to that constraint. I do believe it will not work correctly, since the Pulsar coil relies on on the negative voltage spike to work correctly (to allow the little disc inside to release itself). If it doesn't get that negative voltage spike, it will allow the coil, and hence the valve, to remain activated. It is of particular concern too, since the TOC2 is intended to be discontinued, being in phase-out starting in 2020 (as I recall), and they refer to the MC41 module to replace it. Without the capability to function with the Pulsar coils, that leaves your control options limited to an MC2, or a CANBus-based system (using the MC2, or a combination of master and I/O modules).
I have used the MC41 module though, in a CANBus-based system with an MC2 and XA2, and I must say I am not a fan of the MCx connector system. The tooling is not only expensive, but the signal wires must have an extremely fine insulation diameter to fit in the connector housing (finer than the constraints I have had to work with using the micro timer (MT) part of the TE connector system. Moreover, one part of the literature (MCx) brochure & installation manual) indicates it meets all these great environmental conditions:
To meet the environment found in
mobile machines the MC4 uses
the Molex MX123 high reliability
connector system, made for
harsh environment, high vibration
The enclosure is rated IP66 + IP69K
and is a rugged mechanical design,
sealed for outdoor use.
however the installation manual also states that:
The IQAN-MC4x module must not be placed in any marine related or similar
continuously damp, salt-spray environment without external protection.
I don't know how you can meet a harsh environmental rating but not be usable around a salt spray (which includes coastal, marine, and salt spreader trucks)
The Pulsar valve can still be used, but you need to specify the PF type coil. It is a 90Hz solenoid that is not the digital poppet design that requires the negative spike. The PF version Pulsar works very well with the MC4x controllers. As for the salt spray note, it is always included because of the aluminum enclosures, if the finish were marred, the salt will start reacting with the aluminum.