A Question about Swapping Bytes

bodoo23

Member
Join Date
Jan 2018
Location
Athens
Posts
57
Now, I am working on a project where I need to communicate AB plc with a siemens one. I actually get them communicate with each other but I have a question about swapping.

For example, when sending a dint value(temperature etc) to siemens plc, I need to swap it but there are also dword values which I created bool by bool (start,stop, etc) but they are sent as dword to siemens side. When sending this dword value it is not needed to swap.I didnt understand the reason of this. Dont they recorded memory in same manner ? Why they both dont need swap ?

Thanks in advance.
 
Keep this in mind (using double word address MD 0 as an example):

MD 0 consists of 4 bytes: MB 0, MB 1, MB 2 & MB 3

Byte MB 0 is the most significant and MB 3 is the least

Within the byte MB 0, bit M 0.7 is the most significant, and M 0.0 is the least.

So in the whole double word MD 0, M 0.7 is the highest bit and M 3.0 is the lowest.

Hope that helps.
 

Similar Topics

Hey guys, the scenario is: I have already completed the drawing package for my system utilizing an A-B 440R-N23126 (Minotaur) safety relay. SoS...
Replies
0
Views
165
I have never had the pleasure of working with a "Thermistor" until now and have a question. The Thermistor is a 10KOhm 4-20mA 2-wire device and I...
Replies
0
Views
10
Hi All, So I have a main routine with an instruction that's executed by XIC "Run" I have a JSR located on a rung below it. In the logic for that...
Replies
3
Views
87
I have a 120V relay, 120V DI card and a analog input. I was wanting to know if i could put a 24V DI and well as a 120V DI card on the same plc...
Replies
1
Views
89
Hello again..trying something on an existing poorly written program and just wanted to double check something system is an A-B MicroLogix 1200 In...
Replies
5
Views
197
Back
Top Bottom