The number of Omron Robots that can be controlled by an N series Machine Controller varies according to one of several limiting factors. To assess this for yourself and your application, you should consider the following upper limits which may come into effect, depending on the model of the Machine Controller you evaluate. We have created some guides in the below table as reasonable limits as an initial guide.

1. The amount of Tag Data Link capacity that the Ethernet IP port has. Each ePLC Connect robot connection uses two connections (one input and one output). The size of the connections are 284 byte input and 214 byte output. A built in Ethernet IP port on a MAC controller typically has 19,200 bytes limit and 32 connections max. So provided the MAC has program capacity, variable capacity and CPU capacity, this limit would be 16 robots.
2. The program capacity may limit the number of robots that can be programmed. This depends greatly on the way the movements are programmed (optimized use of one FB for all moves or one FB for each move) 
3. Variable memory capacity (each function block to control the robot gets variables assigned to it so will use program capacity and variable capacity). For the NX1P2 CPU, this is the limit for the number of robots (1), as the minimum function blocks to run the robot would use a considerable amount of the CPU capacity, with some left over for the remainder of the machines program and not the Ethernet IP capacity. Note that positions for the robot may be initialised with initial values and can be Non Retained type, but if teaching robot positions or adjusting from an HMI, then the Retained type must be used. Consider your programs requirements for both types. 
4. How much other Ethernet IP capacity, program capacity and variable capacity the remainder of the machine application may use. This is impossible to OMRON assess and advise, so we have left some spare capacity in the below recommendations so the below table is not the absolute maximum that can be connected. To assess the absolute maximum robots that can be connected, consider your project with the above considerations in mind and find which limit will be reached first. Note we always recommend leaving capacity for later expansion of the control system or machine control capabilities. 

OMRON engineers can help you assess the limit if you are looking to connect many robots to your controller and advise on a practical number for your project and future expansion requirements.

In assessing the reasonable program space required for a Robot control program, we have considered the code required to start up the robot control, the Function block instances ARB_ResetRobotError, \ARB_RobotControl, ARB_Jog, ARB_InputOutputSignals, and ARB_MoveCommand function blocks.

Based on this assumption, we can provide recommendation as below.

*IF using the CJ1W-EIP21 unit, then we can push up to 20 robots as this unit adds Ethernet IP tag data link connections