SRL
The SRL module comes in two different configurations, the SRLM and SRLS. These are the master and slave modules respectively. Using this master/slave configuration, multiple motors can be easily daisy chained by using a simple straight through DB9 serial cable. The SRL modules allow for the use of RS-232 serial communications, as well as quick and convenient access to inputs, outputs, and daisy chaining multiple motors.
The SRL modules also come equipped with a more robust voltage regulation circuit to help deal with any regenerated voltage problems.