Newbie on Modbus+


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Looking at utilizing some de-commissioned equipment and discovered several moth-balled PM 5000's with MB+ cards installed.

Having never used MB+, I looked over Modicon's 'Planning Guide'. A couple of questions?

'Breadboarding' a test setup prior to production.. can I use standard 9 pin D-subs and wire to pins 1, 2, 3 as indicated in the 'Guide'?

Is the shield to be used on pin 2? I've seen comments in my web research indicating otherwise... but the Modicon 'Guide' says something like 'bare wire' to pin 2?

Is it overkill to consider MB+ on point-point over standard MB RTU? The Panelmate application is in excess of 50 pages with numerous alarms... and I thought response time might be improved with MB+.

Any other suggestions.. or if you have experience with the Panelmate Pro units on MB+.... any help would be appreciated.

For testing purposes only, you can use a DB9 jumper cable (1:1) with a gender bender on one end. I use these all the time in my test lab. No need to worry about terminations or "cut" lengths.

When wiring a control network, use all 3 wires and ONLY use recommended cable.

Modbus Plus protocol runs at 1 Meg vs 19.2 KB for serial. Throughput is about 20,000 registers per second. Even for point to point I would consider using it over Modbus RTU (serial). The distance is 1500 feet before a repeater is required (max 6000 feet on copper).