T-Series/Commands/Set Hold Current/Motorized NMC Devices

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Instruction Name Set Hold Current
Applies to T-LSQ, T-LST, T-MCA, A-series and X-Series motorized devices
Firmware Version 5.00 and up
Command Number 39
Command Type Setting
Command Data Value
Reply Data Value
Safe to retry? Yes
Returns Current Position? No
Persistence Non-Volatile
Summary Sets the desired current to be used when the device is holding its position.

It is typical to run stepper motors at their rated current when they are moving (run current) and reduce the current when idle to hold the position (hold current). When a device stops moving, it switches from using the run current to the hold current 0.1 seconds later. This setting specifies the maximum hold current that may be used on each motor phase. If the motor position is between full steps, each phase will use some fraction of the current specified by this setting. Typically the hold current can be set to around 25 - 50% of the running current. In some applications, the friction of the drive system alone is sufficient to hold the microstep position of the motor, and the hold current can be turned off completely. The hold current can be turned off by issuing the "Set Hold Current" instruction with data of 0.

The value of the hold current setting is in 20 mA DC increments. As an example, to convert a desired hold current of 800 mA DC into a data value for this setting:

data value = 800 mA DC ÷ 20 mA DC/data = 40

To determine the actual current given the data value 40:

current = 40 × 20 mA DC/data = 800 mA DC