The serial option card gives you a way to communicate with any GSD8 Digital DC Drive
over RS232 or 485 that supports option cards.
That means you can control and monitor anything available in the drive from a PLC, a SCADA
system or even your personal computer.
It also has an analog input that can be configured to use a potentiometer or resistive input,
a voltage input or a current input.
The analog input can be used to control the target speed and % Speed.
It can serve as the tachometer input or the leader tach signal and it can control a frequency
generator output pulse rate.
The frequency generator output pulse rate can reflect the analog input level, the motor
speed, a fixed rate which is set in parameter 5032, or the status of the alarm output.
There is a two-pin header that can be used to control where the speed reference comes
from: manually via the front panel or automatically from this card, which could be the analog
input or the serial channel.
Let’s do a quick example of how to set up the serial coms.
I’m using the same setup that we used in the previous videos: I have this GSD8 drive,
connected to this motor, which has this encoder which goes back to the drive to complete the
feedback loop.
I also have jog and inhibit wired and an indicator connected to the alarm relay output.
Before plugging the com card into the drive, I wired a switch to this auto manual terminal,
made sure the RS232 RS485 jumper was set for RS232 and plugged an ethernet patch cord into
the RJ45 jack because I find it’s easier to do that with the card outside the drive.
Next, I just plug the card into option slot 500.
Slot 500 is the ONLY slot this serial com card will work in.
When you apply power to the drive, you see a message in the display asking if you want
to configure the com card.
Press up arrow to do it.
Let’s go to parameter 95 and enter a 5 to reset our drive so we are starting from a
known configuration – which defaults to Rate Mode.
Up arrow to confirm.
And let’s also reset the com card to factory default
which is parameter 96, and we want to reset the card in slot 500.
Up arrow to confirm.
That’s it!
We are ready to go.
To keep things simple, I’m going to use my desktop computer to talk to the drive.
It doesn’t have a serial port, so I used this USB to 232 converter, a female DB9 connecter
wired like this and this ziplink RJ45 breakout board so I could easily wire my serial data
into the drives RJ45 cable.
This wiring diagram only works if you have a straight through RJ45 patch cable.
If you have a crossover cable, you’ll need to modify the wiring accordingly.
Let’s go to the device manager on my PC and make a note of which com port the USB
to serial cable is using.
You can use any terminal emulator program you want, I like this TeraTerm program because
it’s quick it’s simple and it’s free.
But, it is NOT and AutomationDirect product, so please, don’t call tech support asking
how to use it.
They won’t be able to help you.
Just make sure that whatever terminal program you are using is using the right com port
– we are using this one – yours will probably be different – and that the port parameters
are set to 9600 baud, no parity, 8 bits, and one stop bit because that’s what the com
card defaults to.
This is how I have the terminal program configured.
If I type an “AS01” and hit enter, the drive returns the actual speed, which is zero
right now.
So I’ll increase the speed a bit, then type “AS01” again and now we see the new drive
speed.
There are only 6 commands: SP is set target speed.
SV is set variable.
RV is read variable.
AS is get actual speed.
TS is get target speed.
And AL is the alarm state.
They all start with the two-letter command, followed by a two-digit address.
That’s the address of your com card which is in parameter 5020.
The default address is 01.
And yes, you do need to include the correct address even if you are only using RS232.
The address is always followed by a comma and however many parameters that command needs,
also separated by commas.
A final carriage return finishes the command.
We are currently at this speed, so let’s try to change that with a set speed command, at
address 1, and let’s set the speed to 250 rpm.
Hit return and we get an “N.” The “N” says the command wasn’t executed, which
we know because the drive speed didn’t change.
What happened?
Well, the drive is currently in manual mode – it’s expecting speed commands to be
entered manually from the front panel.
We can see that because this blinking LED is telling us we are in manual mode.
It’s blinking to warn us that we have a com card installed but the drive is in manual
mode.
To fix that, we need to go to parameter 120, to change it to a 2 to tell the drive that
the option card in slot 500 will control the auto manual mode.
Scroll to zero and press enter to exit parameter entry mode.
Let's do a read value from device 1, parameter 120.
Yep, it’s a 2 now.
I’ll flip our auto manual switch to auto and look – the LED is now solid telling
us we are in auto mode and the drive stopped.
That’s because we haven’t entered a speed in auto mode yet.
So now if we do a set speed at drive 1, at this rate, the drive responds accordingly, AND we got a “Y”
to confirm that the drive executed the command.
Let’s get the target speed from device 1.
Perfect.
By the way, if you send a command to the wrong address or send a bad command, nothing happens,
you don’t even get an “N.” Send the correct command and everything works
again.
OK, let’s set variable at drive 1, 5020 to a 2.
That will change the drive's address to a 2 and we see
we got the confirmation “Y.”
Now if I try to get the actual speed at drive 1, we get nothing.
But if I get the actual seed from drive 2, we do see the speed!
Let’s read variable, from drive 2, parameter 1 which is the model number.
And there it is!
So that’s it!
You can now control and monitor anything you want in the drive using just 6 commands.
And all we did to set that up was reset the drive, reset the option card, and tell the
drive which option card was in charge of the auto manual function.
By the way, you can also switch the auto manual mode by double-clicking the enter key
if you set parameter 18 to a 5.
That’s a handy thing to know.
As a side note, I like to use an O-Scope to debug my serial coms, so since I had it set up,
I thought I would share it with you.
Here you can see each character as I type it and when I hit the final return, you see
the reply from the drive.
Looks like on my system, the response time is about 7 milliseconds.
You might need to know that when programming your controller.
Which reminds me, there are example programs for both the BRX and Productivity PLCs in
the back of the com card manual.
This option card only adds 11 parameters so go take a look at them to see how to set up
the analog input and frequency generator.
Well, that ought to be enough to get you up and running with the com card and the GSD8
family of Digital DC Drives.
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