THIS PRODUCT IS NOT RECOMMENDED FOR NEW APPLICATIONS:
- OCM-101 DHC Series Modbus Option Module
Click here for Datasheet: 800-160C PDF 
Click here for Modbus User's Guide: 800-161C PDF
REPLACEMENT PRODUCT:
- OCM-102 DHC Series Modbus Option Module
Click here for Datasheet: 800-191A PDF
Click here for Modbus User's Guide: 800-192A PDF
Replacing OCM-101 with OCM-102 (refer to Datasheets for complete details)
MECHANICAL
The OCM-102 has the same package and mounting dimensions, allowing it to directly replace an OCM-101.
ELECTRICAL
The electrical connections to the OCM-102 are identical to the OCM-101.
FUNCTIONAL
As a direct replacement of the OCM-101, the OCM-102 will provide the same response as the OCM-101 to any of the Modbus functions. For Modbus Functions $03 and $06, the OCM-102 response is much faster, providing near zero latency - see Section V in the Modbus User's Guide for more details.
If the user defined Function $41 is used with the OCM-101, it should be noted that the OCM-102 will experience an additional delay if a Function $03 request follows a Function $41 request. The OCM-102 will provide an immediate exception response of $0B, and will continue to do so for subsequent Function $03 requests, until the delay period is over - see Section I in the Modbus User's Guide for more details.
The OCM-102 allows multiple registers to be requested with Function $03, where the OCM-101 is limited to requesting a single register only.