Internet PLC Forum

General => Technical support => Topic started by: eagroup on September 03, 2010, 10:47:21 AM

Title: ReadMB2 Number of Registers
Post by: eagroup on September 03, 2010, 10:47:21 AM

The M-series READMB2 command is limited to reading 16 registers.  Has this been increased for the Nano or F-series?  I need to read 250 registers from 4 devices and I'd rather read them, for instance, 100 at a time.

Thank You.

Title: Re:ReadMB2 Number of Registers
Post by: support on September 06, 2010, 03:09:55 PM

The current limit of READMB2 command for Nano-10 and F-series PLCs 32 words per read command.

Title: Re:ReadMB2 Number of Registers
Post by: eagroup on September 07, 2010, 09:20:25 AM

Similarly, when the M- or F-series is acting as a slave, how many registers can be requested at a time by the master over RTU or over TCP?

Thank You

Title: Re:ReadMB2 Number of Registers
Post by: support on September 07, 2010, 04:32:13 PM

As a Modbus RTU or Modbus TCP slave you can access 122 data point max.

As a Modbus ASCII slave you can access only half the number (61).