But you haven't told us what you have connected, where. You have connected grounds, right?
Ok, right. Attached is my wiring diagram. There is too much info on there, which is why I didn't post it. I also use a custom shield, so didn't want to confuse anyone. The serial pins connect directly to the stepper drive. Definitely, all grounds are connected.
Anyway, the drive came with a special cable- DB9 on one side and RJ11 on the other to connect to the drive. I cut the cable (I have a few extras), and by doing a continuity test I determined which were tx and rx and gnd. I confirmed this by doing another test with the RJ11 side, as indicated on page 75 of the SCL manual. I connected the tx, rx, and gnd from that cut cable directly to the arduino Serial3 pins D14 and D15. I did this cable cut method to get the drive working with a PLC (as instructed by AutomationDirect) on several occasions, and worked like a charm. I used this PLC:http://www.automationdirect.com/adc/Shopping/Catalog/Programmable_Controllers/CLICK_Series_PLCs_(Stackable_Micro_Brick)/PLC_Units/C0-01DR-D
Are you using a MAX232 between the device and the Arduino? It looks to me like the device expects to be connected to a PC's serial port, which is NOT TTL serial, like the Arduino.
I was of the understanding that an Arduino could communicated directly with a computer. And if that is the case, I figured that the Arduino could connect directly to the stepper drive just as well. I have the Arduino connected directly to the stepper drive, no MAX232 between.Thanks so much for replying to my question. I've done a lot of hardware work, but I'm fairly light on serial communication protocols.
Here's some more info on the drive. http://www.automationdirect.com/static/manuals/surestepmanual/surestepdrive2_datasheet.pdf