The Schneider/Modicon "Modbus II" Protocol

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Thread Starter

Lynn Linse

Whenever you connect with ModSoft to a com port, you have a number of protocol options including "Modbus II".

A while ago I was verbally told by someone at Schneider that this was a derivative of Modbus-Plus designed to be tunneled across a serial link. It looked like Modbus/RTU with RTU CRC, but instead of the 1-byte Slave address of RTU it had the 5-byte path of ModbusPlus. This allowed the MB+ message to bridge thru serial links without loss of the path.

I'm curious if anyone out there has ever seen a formal definition of this "Modbus II" & can confirm this?

Thanks

Lynn August Linse, Senior Product Application Engineer
15353 Barranca Parkway, Lantronix Inc, Irvine CA 92618
[email protected] www.lantronix.com
Tel: (949)300-6337 Fax: (949)453-7132
 
Modbus II is a MAP3.0 compatible protocol. Media is coax cable and speed could be up to 5/10M. Since it's some what expensive, few users use it, so. It's not present in current product line. The core net work for time being for Schneider is Web enabled TCP/IP Ethernet, up to 100MB.
 
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Rob Entzinger

Modbus II is base on Manufacturing Automation Protocol (MAP) and runs on a coax cable. I think it was base on the MC68824 Token bus controller. It operates at 5Mbps, supporting upto 64 stations (addresses 1-255)which function as peer members of a token-passing logical ring.

Refer to manual GM-MBII-04A revision AX03.

Hope this helps
Rob E.
 
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Lynn --
The Modbus II protocol is a mini-MAP protocol, using 3 of the 7 layers of the MAP protocol. The message encoding was MMFS, and the link layer was of token bus design. It predates Modbus+.

The formal definition is in the MODICON Modbus II Network Subroutine Library User's Guide (GM-MBII-04A).

Rich Baker
Engineering Manager
(including the Modbus II project in the late 1980s)
Schneider Automation
 
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Phillip O'Meley

Modbus II was pre IEE 802.4 days. In my market place (Oz) it wasn't pursued when MB+ arrived in the early 90's
Regards
Phill O'Meley
 
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