Driver DIP-switch selector

How it is worked out

The tool does not calculate a pattern. It looks the motor’s rated current up in the current table printed in the drive’s own manual, and picks the highest setting that is not above it. Every row on this page is copied from the manual named under its table.

setting  = the highest table current that is not above the motor’s rated phase current
next up  = the row after it: shown for reference, never chosen, because it exceeds the rating

Worked example. A NEMA 23 motor rated 2.8 A per phase, on a Tstep-087-485. The drive’s table steps 0.6, 1.6, 2.6 and 3.6 A, and on to 7.0 A. The highest step not above 2.8 A is 2.6 A, which the manual sets as S1 ON, S2 OFF, S3 ON. The next step, 3.6 A, would drive the motor 0.8 A over its rating. On a Tstep-087 the same motor gets exactly 2.8 A: J1 and J2 removed, J3 and J4 mounted.

Rated current, peak or RMS

The current tables in these manuals give a plain “Current (A)”, and none of them says whether the figure is peak or RMS. What each manual does say is to set the drive to the motor’s rated phase current, and the Modbus manual adds “or below”. So the table figure is compared directly with the rated current on the motor’s datasheet, and the setting never goes above it.

For 6-lead and 8-lead motors, the wiring pages of the same manuals give a fraction of the rated current to set for each way of connecting the windings. Work that figure out first and enter it as the rated current.

Reading the drawing

• Tstep-087-485: a 10-way DIP switch, S1 to S10 from left to right as on the switch block. Each lever is drawn at its ON end or its OFF end; match the drawing to the ON mark printed on the switch itself. ON is closed: firmware 2.00 reads a closed switch as low and counts it as 1.
• Tstep-087: the CSET jumper block, positions 1 to 4. A shunt drawn over both pins is 1, jumper mounted; bare pins are 0, jumper removed, which is how the manual’s table is written.
• A dashed slot with no lever is a switch the table does not set: a reserved switch, or the current switches when no setting fits the motor.

When a change takes effect

On firmware 2.00, S1 to S3 change the motor current at once, even with the motor running, so set them with the motor stopped. S4 to S8 are read once at power-up: change them, then power-cycle the drive. Neither the address nor the baud rate can be changed over the bus.

Tstep-087-485 address and baud rate

Firmware 2.00 speaks Modbus RTU. Its address table follows one rule, which is also how the firmware reads the switches:

Address = 1 + (1·S4 + 2·S5 + 4·S6 + 8·S7)      a switch that is ON counts as 1
S8 OFF = 19200 baud      S8 ON = 115200 baud

All four address switches off is address 1, and all four on is address 16. S9 and S10 are unused on firmware 2.00, and their position has no effect.

The original firmware, described in the 2021 manual, uses the same current switches but a different bus setup: addresses 0 to 15 with the switch sense reversed, 9600 or 38400 baud, and S9 and S10 choosing one of four operation modes. A drive that answers Modbus RTU runs firmware 2.00, and its register 0x0001 reads 0x0200. A drive set up with the RS485 Online and Offline demo programs runs the original firmware. Pick the matching entry in the model list, because the same switch pattern means a different address on each.

What the switches do not set

• Microstepping is fixed at 10 on all three entries: 2000 steps per revolution on a 1.8° motor.
• The Tstep-087 manual and the original Tstep-087-485 manual give automatic current reduction to 70% of the set current after about one second without steps. No switch selects it.

Drives not listed

The Tstep-087X, Tstep-117X, Tstep-168X and Tstep-484 are not in this tool. Set them from the current table supplied with the drive.

Related products

• Tstep-087-485 Stepper Driver: RS-485 stepper drive with switch-set current, address and baud rate.
• Tstep-087 Stepper Driver: 18–80 V DC, current set by jumper from 1.2 A to 7.0 A, 10 microsteps.